http://www.spoj.com/problems/ADAJOBS/

URI 2226 (5) //[NICE][NUMBERS][DP]

http://www.spoj.com/problems/SUB_PROB/en/

http://codeforces.com/contest/696/problem/D 8

http://www.spoj.com/problems/AHOCUR/ 5 //Aho-Corassic + DP

https://www.codechef.com/problems/LYRC (5) //Sample aho-brute-force

http://codeforces.com/problemset/problem/346/B //Proposed by bradyawn

6861 [LA] //CYK

UVA 10679 //Suffix Automat

http://www.spoj.com/problems/STRMATCH/ //Suffix Automat — trie might do too

http://www.spoj.com/problems/NSUBSTR2/ //Suffix Automaton

UVA 12519

http://www.spoj.com/problems/ARBITRAG/ (4) //Or Floyd-Warshall

http://www.spoj.com/problems/ADACYCLE/ [FW]

UVA 13295 (6) //[NICE][EFFICIENCY][IMPLEMENTATION]

http://codeforces.com/gym/101992/problem/H (4) //[VERY NICE][MAX]

http://codeforces.com/gym/100112 H

6151 — Beehives (4) //[NICE] //Search for shortest cycle

https://devskill.com/CodingProblems/ViewProblem/60

https://devskill.com/CodingProblems/ViewProblem/150

11312 UVA (3)

11392 UVA (4)

http://codeforces.com/contest/653/problem/E (6)

http://codeforces.com/contest/769/problem/C 5 //FL:ODD/**** | bfs+greed NICE

10968 UVA (3) //EASY + NICE (bfs withot <=2 nodes)

http://codeforces.com/contest/796/problem/D (3) //NICE+EASY ... print visited in bfs (not par)

10888 UVA (4) //VERY NICE — but not main technique ... ++ DP /or/ MCMF

http://codeforces.com/contest/821/problem/D (5) //VERY NICE — Consider only points not GRID

http://www.spoj.com/problems/DIGOKEYS/ (4) //Easy [Nice problem — weird statement]

http://www.spoj.com/problems/SPIKES/ (3) //Easy bfs (# of 's' * 2)

http://www.spoj.com/problems/MULTII/ (4) //VERY NICE: BFS over numbers (K*10+d)%N

http://www.spoj.com/problems/ADV04F1/ (5) //VERY NICE: [imple] ~ N^4*BigConstant

http://www.spoj.com/problems/INVESORT/ (5) //Big limit (really usefull :P)

http://codeforces.com/contest/59/problem/E (5) //[NICE][DOUBLE-STATES][SET]

http://codeforces.com/contest/877/problem/D (4) //[NICE] Add vector to # of states

4291 — Sculpture (6) //[NICE][PREPROCESS][NORMALIZE]

10977 UVA (3)

928 UVA (3)

13116 UVA (4)

314 UVA (3)

11487 UVA (4)

5622 LA (7)

11931 UVA (5)

http://www.spoj.com/problems/KNMOVE/ 3 //simple knights

http://www.spoj.com/problems/SERGRID/ 3 //almost classical

http://www.spoj.com/problems/NAKANJ/ 3 //Classical chess — KNIGHT

http://www.spoj.com/problems/PUCMM223/ (4) //NICE (but not many languages) — 2 moving [x][y]

http://www.spoj.com/problems/SPIRALGR/ (4) //NICE (not typical) [SIEVE]

http://www.spoj.com/problems/DCEPC706/ (4) //NICE — travelling outside

http://codeforces.com/contest/35/problem/C (3) //No obstacles [multiple starts]

https://devskill.com/CodingProblems/ViewProblem/394 (2) //Multiplication (or math)

http://codeforces.com/contest/66/problem/A (2) //Big + iffs + implementation

UVA — 10183

10106 — Product [UVA]

10523 — Very Easy !!! [UVA]

787 — Maximum Sub-sequence Product [UVA]

2871 — Rhyme Schemes [LA][BELL]

UVA — 10497

http://www.spoj.com/problems/MUL/en/

http://www.spoj.com/problems/ITRIX_E/

11115 — Uncle Jack

11448 — Who said crisis? [UVA]

http://www.spoj.com/problems/GCD2/

10083 — Division [UVA]

11830 — Contract Revision [UVA]

1230 — MODEX [UVA]

http://www.spoj.com/problems/NUMPLAY/

10519 — UVA

7651 — Pascal's Hyper-Pyramids [LA]

11344 — The Huge One [UVA]

10303 — How Many Trees? [UVA]

http://www.spoj.com/problems/FAST2/

495 — Fibonacci Freeze [UVA]

10023 — Square root [UVA]

http://www.spoj.com/problems/SKYLINE/

http://www.spoj.com/problems/NITT2/

11879 — Multiple of 17

http://www.spoj.com/problems/MINNUM/

10494 — If We Were a Child Again [UVA]

10013 — Super long sums [UVA]

10925 — Krakovia [UVA]

10814 — Simplifying Fractions [UVA]

619 — Numerically Speaking [UVA]

713 — Adding Reversed Numbers [UVA]

1226 — Numerical surprises [UVA]

623 — 500! [UVA]

http://codeforces.com/problemset/problem/18/D

http://www.spoj.com/problems/NUMTSN/

https://www.codechef.com/problems/FRJUMP

10220 — I Love Big Numbers ! [UVA]

https://www.hackerrank.com/contests/projecteuler/challenges/euler025

https://www.hackerrank.com/contests/projecteuler/challenges/euler020

11645 UVA 4

Gym — 100866A [ACM ICPC 2005–2006 NEERC Moscow Subregional Contest]

CSQUARE [SPOJ]

http://www.spoj.com/problems/PARCARD1/

10070 — Leap Year or Not Leap Year and .. [UVA]

http://www.spoj.com/problems/SOLDIERS/

12333 — Revenge of Fibonacci [UVA]

http://www.spoj.com/problems/NDIVPHI/

http://www.spoj.com/problems/IWGBS/ [UVA]

http://www.spoj.com/problems/POP3/ [Prime-Test]

http://www.spoj.com/problems/VGCD/

http://www.spoj.com/problems/NDIVPHI2/

12924 — Immortal Rabbits [UVA]

Count the Trees [UVA][10007]

10198 — Counting [UVA]

11375 UVA 3

http://www.spoj.com/problems/MINNUM/ 3 // BIG/9+!!(BIG%9)

10844 UVA 4 //Bell numbers + big (might be slightly slow!)

http://www.spoj.com/problems/NITT2/ 2 //Divisibility by two constants

http://www.spoj.com/problems/NUMPLAY/ (3) //With DP

http://www.spoj.com/problems/IWGBS/ (3) //Fibonacci 10^4

http://www.spoj.com/problems/PUCMM025/ (2) //Divisibility by 1 → 9

http://www.spoj.com/problems/CSQUARE/ (3) //Converse + Power

http://codeforces.com/contest/17/problem/D (5) //B^(N-1)*(B-1)%C [B/N are big]

https://codeforces.com/contest/1173/problem/C (4) //[NICE]

https://codeforces.com/contest/1201/problem/C (4) //[NICE][SIMPLE]

https://codeforces.com/contest/1183/problem/C (3) //[SIMPLE][NICE]

http://codeforces.com/gym/101628/problem/J (4) //[NICE][EASY]

http://codeforces.com/gym/101962 F //[NICE][FW]

http://codeforces.com/contest/920/problem/G (5) //[NICE][MATH][IE]

http://codeforces.com/contest/140/problem/C (4) //[NICE][GREEDY]

http://codeforces.com/contest/898/problem/E (4) //[NICE][SIMPLE][PREPROCESS]

http://codeforces.com/contest/888/problem/C (3) //Can be done without BS

http://codeforces.com/contest/68/problem/B (3) //[EASY][DOUBLE]

http://codeforces.com/contest/42/problem/A (2) //Or simple math

http://codeforces.com/contest/883/problem/I (4) //[NICE][SET][2Pointers]

http://codeforces.com/contest/51/problem/C (4) //[NICE][GREEDY-CHECK]

http://codeforces.com/contest/729/problem/C 3

http://codeforces.com/contest/714/problem/D 8

13150 (UVA) 4

http://codeforces.com/contest/749/problem/D 5

11692 (UVA) 4

11516 (UVA) 3

http://codeforces.com/contest/760/problem/B 3

http://codeforces.com/contest/675/problem/D 4 //dunno — solvable with treap

http://www.spoj.com/problems/NDS/ 4 //BS over LIS

http://www.spoj.com/problems/VECTAR4/ 3

http://codeforces.com/contest/767/problem/D 4 //NICE

http://codeforces.com/contest/627/problem/D (7) //with dp — NICE

http://codeforces.com/contest/779/problem/D (3) //NICE + EASY

http://www.spoj.com/problems/CNTINDX/ (4) //Map+BS === OK

13177 UVA (3) //BS over answer == OK

http://codeforces.com/contest/801/problem/C (3) //BS + SUM -EASY

http://codeforces.com/contest/803/problem/D (3) //BS by answer

http://codeforces.com/contest/807/problem/C (3) //Or math

http://codeforces.com/contest/818/problem/F (4) //NICE — Live VS Clique

http://codeforces.com/contest/845/problem/E (5) //VERY NICE — min(X,Y) .. add time, repeat

http://www.spoj.com/problems/MATHLOVE/ (2) //BS + Gaus (or otter ways)

http://www.spoj.com/problems/SABBIRGAME/ (3) //Binary search over answer ::max(0,ANS)

http://codeforces.com/contest/846/problem/D (4) //BS+Precalculation OR 2D-RMQ

http://www.spoj.com/problems/RPLC/ (3) //Classical

http://www.spoj.com/problems/TRIGALGE/ (2) //On doubles — simple function given

http://www.spoj.com/problems/ABA12E/ (4) //VERY NICE — BS on answer + 2Pointers

http://codeforces.com/contest/847/problem/E (4) //NICE: Back+Front OR Front+Back

http://www.spoj.com/problems/MAIN8_C/ (3) //Classical — simultion over array

http://www.spoj.com/problems/FUNFACT/ (4) //VERY NICE — Sterling Approximation

http://codeforces.com/contest/16/problem/C (3) //[or math][simple formula check]

http://codeforces.com/contest/21/problem/C (3) //[NICE][prefix-sum+lower_bound]

http://codeforces.com/contest/24/problem/E (5) //[doubles]

http://codeforces.com/contest/875/problem/E (6) //VERY NICE [BS][Keep possible places]

https://devskill.com/CodingProblems/ViewProblem/566 (2)

https://codeforces.com/gym/102006/problem/F (6) //[VERY NICE][DP]

http://codeforces.com/gym/101908/problem/I (3) //[EASY][XOR]

http://codeforces.com/contest/879/problem/C (3) //[NICE] one of each operation is enough

http://codeforces.com/contest/92/problem/B (2) //Bit addition/shifting (but big number)

http://codeforces.com/contest/907/problem/C (3) //Nice but ugly statement: sets

11659 UVA (4)

11535 UVA (4)

http://codeforces.com/contest/779/problem/E (5) //NICE + Parsing

http://www.spoj.com/problems/EC_CONB/ (1) //reverse numbers

http://codeforces.com/contest/769/problem/D (4) //freq + brute-force

http://www.spoj.com/problems/HAP01/ (2) //builtin_popcount

http://codeforces.com/contest/862/problem/C (3) //VERY NICE — Random works well

http://www.spoj.com/problems/KOMPICI/ (4) //NICE — Bitmask over digits

http://www.spoj.com/problems/ADACOINS/

http://www.spoj.com/problems/ADACHERY/

http://www.spoj.com/problems/ADAFUROW/

https://codeforces.com/contest/1194/problem/E (5) //[NICE][BRUTE]

https://www.spoj.com/problems/TTRGRAPH/ (4) //[NICE][GRAPH][CLIQUES]

https://www.spoj.com/problems/ILD18ACP/ (5) //[NICE][GRAPH][PATH]

http://codeforces.com/contest/914/problem/F (7) //[VERY NICE][POLYMUL-LIKE][BRUTE]

http://codeforces.com/contest/117/problem/C (5) //Finding 3cycles in directed graph [NICE]

http://codeforces.com/contest/754/problem/E 6

http://www.spoj.com/problems/UCBINTC/ 5 //polymul with bitset

http://codeforces.com/contest/33/problem/D (4) //VERY NICE [LCA works too]

http://codeforces.com/contest/918/problem/C (4) //Brute-force+Bitset (or...)

http://codeforces.com/contest/118/problem/E (4) //[NICE]//Orientation [+DFS]

315 — Network

796 — Critical Links

UVA 12363

Gym 100114J [2012-2013 ACM-ICPC, NEERC, Central Subregional Contest]

http://www.spoj.com/problems/ONBRIDGE/ [ONLINE][HARD][NICE][D&C]

http://codeforces.com/contest/732/problem/F 7

http://codeforces.com/contest/700/problem/C 7

http://www.spoj.com/problems/EC_P/ (3) //bridges ONLY

http://www.spoj.com/problems/SUBMERGE/ (3) //Direct articulation

http://www.spoj.com/problems/GRAFFDEF/ (5) //Bridge tree

http://codeforces.com/contest/1000/problem/E // Sugested by Warawreh

https://www.spoj.com/problems/YOSEQ/ (3) //[NICE][OBSERVATION]

UVA 13296 (5) //[NICE][RECURSION]

http://codeforces.com/gym/100112 (7) [L] //[PRECISION]

http://codeforces.com/gym/101806/problem/X (6) //[VERY NICE][DFS][IFS][OBSERVATION]

8259 — High Score LA //[VERY NICE][TS works too] add only low number to minimum (NOT WORKING?)

http://codeforces.com/contest/922/problem/B (2) //Test all pairs — observe 3rd

http://codeforces.com/contest/919/problem/B (1) //Simply simulate

http://codeforces.com/contest/146/problem/B (2) //Test all bigger numbers

http://codeforces.com/contest/911/problem/B (1)

7692 — Square Deal (4) //Permutations+Swap

http://codeforces.com/contest/907/problem/A (2) //try all triples 0→ 200

http://codeforces.com/contest/124/problem/B (3) //next-permutation

http://codeforces.com/contest/910/problem/C (3) //Next-permutation

http://codeforces.com/contest/898/problem/B (2) //Try all possibilities

6160 — Countdown (5) //[NICE][DFS][EFFICIENT?]

http://codeforces.com/contest/122/problem/C (3) //Just around 2^10 lucky [RECURSION]

7899 — Mr. Panda and Strips (4) //Weak test-cases

7671 What a Beautiful Lake (2) //Try up/down from every node

http://codeforces.com/contest/110/problem/A (1) //4 or 7

http://codeforces.com/contest/106/problem/B (2) //Cycles -_-

http://codeforces.com/contest/895/problem/A (2) //All segments [in circle]

http://codeforces.com/contest/893/problem/B (2) //Try each divisor

http://codeforces.com/contest/894/problem/A (1) //3-cycles

http://codeforces.com/contest/892/problem/C (3) //Try to find "1" ASAP

http://codeforces.com/contest/102/problem/A (2) //Iterate over all triples

http://codeforces.com/contest/96/problem/B (2) //Check all

http://codeforces.com/contest/94/problem/B (1) //3cycles

http://codeforces.com/contest/887/problem/B (3) //Test all numbers

http://codeforces.com/gym/101597/problem/A (4) //[MATH][MODULO][SIMULATION]

http://codeforces.com/contest/68/problem/C (5) //[VERY NICE][RECURSION][MAX COST MIN FLOW]

http://codeforces.com/contest/68/problem/A (1) //Simple simulation

http://codeforces.com/contest/66/problem/B (2) //Test always whole platform

http://codeforces.com/contest/879/problem/C (3) //[NICE] one of each operation is enough

http://codeforces.com/contest/46/problem/C (2) //[2pointers][N^2 works too]

http://codeforces.com/contest/47/problem/D (4) //[Implementation][DFS]

http://codeforces.com/contest/51/problem/D (4) //Check all/check without 1s/2nd

http://code-festival-2017-qualc.contest.atcoder.jp/tasks/code_festival_2017_qualc_b (2)

http://codeforces.com/contest/53/problem/B (3) //at most 60 possibilities

http://codeforces.com/contest/55/problem/B (3) //Try all permutations & possibilities [NICE]

http://codeforces.com/contest/877/problem/B (3) //NICE [N^2][PrefixSum]

LA 6623 — Battle for Silver (3) //4 for-cycles inside ~ K4 search

UVA 12169 (2)

http://codeforces.com/contest/725/problem/C 4

http://codeforces.com/contest/725/problem/E 6

http://codeforces.com/contest/724/problem/B 3

11961 UVA (2)

11898 UVA (4)

11659 UVA (4)

http://codeforces.com/contest/753/problem/C 7

11699 UVA (4)

11548 UVA (3)

11471 UVA (5) //With dynamic programming

http://codeforces.com/contest/698/problem/D 8 //with geometry

http://codeforces.com/gym/101840 F //[NICE][BS][DISTANCE]

11206 UVA (6) //4^20 (but somehow passes)

11214 UVA (6) //Úvaha + pruning

11127 UVA (4) //Simple dfs [just realize you can do so]

http://www.spoj.com/problems/BOKAM143SOU/ (3) //just implement for-cycles

http://www.spoj.com/problems/BLOPER/ (4) dfs with little pruning

13173 UVA (3) //just brute-force + branching

http://codeforces.com/contest/799/problem/D (4) //VERY NICE [only top 34 needed] — trick with 2 [~20]

10890 UVA (4) //Simple brute-force times out, but with simple pruning AC (answer detection

http://codeforces.com/contest/813/problem/B (3) //All*All (BF) care for overflow! NICE & EASY

http://codeforces.com/contest/817/problem/C (3) //Check S+Constant (NICE!)

10732 UVA (2) //Brute-force passes .. just don't trust them O(N^2)

10748 UVA (5) //VERY Nice (knights have K^2 moves not 8^K)

http://codeforces.com/contest/818/problem/D (4) //NICE for each 'A' check all remaining (max SQRT)

http://codeforces.com/contest/834/problem/E (5) //NICE — hard to imple: all 11122...999 OK

http://www.spoj.com/problems/JHAGIRLS/ (4) //Efficient — or store output in array

http://codeforces.com/contest/846/problem/B (3) //Brute-force

http://www.spoj.com/problems/ALONE/ (4) //Generate everything <10^15 [NICE]

http://codeforces.com/contest/861/problem/B (3) //Check all floor-sizes

http://www.spoj.com/problems/RRANGE/ (3) //Compare all queries agains all updates + GAUSS

http://codeforces.com/contest/598/problem/B (3) //Treap works too ;-)

http://www.spoj.com/problems/AMR10I/ (4) //Can be solved with brute-force with dp

http://codeforces.com/contest/868/problem/C (4) //Brute-force (fixet at most 6 each bits)

http://codeforces.com/contest/868/problem/D (5) //NICE: Maximal K is low (I assumed 15)

http://codeforces.com/contest/31/problem/C (2) //LOW-Constaints: N^2

http://codeforces.com/contest/32/problem/D (3) //Simply try all possibilities

http://codeforces.com/contest/876/problem/C (3) //Try N and ~100 lower

http://codeforces.com/contest/44/problem/B (2) //N^2 works fine

https://codeforces.com/gym/101991/problem/A (5) //[VERY NICE][FW]

http://codeforces.com/gym/101864 D //[NICE][SACK][ARPA][HLD]

http://codeforces.com/gym/101840 E //NICE

DCP-176: Motku2 [DevSkills]

http://codeforces.com/contest/715/problem/C 9

http://codeforces.com/contest/741/problem/D 8

13164 UVA (7)

http://codeforces.com/contest/752/problem/F 5

http://codeforces.com/contest/766/problem/E 6

http://codeforces.com/contest/833/problem/D 7 //Very nice — hard (thinking + imple) + FW

http://www.spoj.com/problems/HOLI/ (4) //VERY NICE: 2*Distances from centroids

https://codeforces.com/gym/102006/problem/K (6) //[VERY NICE][THEOREM][OBSERVATION]

http://codeforces.com/contest/741/problem/C 6

11331 UVA (4)

http://codeforces.com/contest/664/problem/D 4

http://www.spoj.com/problems/ADATEAMS/

http://www.spoj.com/problems/ADASUM/

https://codeforces.com/contest/1173/problem/D (4) //[VERY NICE][DFS][FACTORIAL]

https://atcoder.jp/contests/abc136/tasks/abc136_f (5) //[VERY NICE][IE][POWER][FENWICK]

https://codeforces.com/contest/1178/problem/C (3) //[NICE][EASY][POWER]

https://codeforces.com/gym/101972/problem/J (4) //[NICE][THEOREM][COMB-NUMBERS]

https://codeforces.com/gym/101972/problem/I (5) //[NICE][SHORT][COMB-NUMBERS]

http://codeforces.com/gym/101628/problem/G (5) //[NICE][COMB-NUMBERS]

http://codeforces.com/gym/101864 E //Combination number, power

http://codeforces.com/gym/101879/problem/E (2) //Power of 2

http://codeforces.com/gym/101873 (5) //Necklace (mby burnside)

http://codeforces.com/gym/101808/problem/F (3) //[EASY]][FACTORIAL]

http://codeforces.com/problemset/problem/364/A (4) //[NICE][STL-or-sorting][IF]

http://codeforces.com/contest/145/problem/D (7) //[VERY NICE][SET][OBSERVATION][BS][BIG]

http://codeforces.com/contest/909/problem/B (3)

http://codeforces.com/contest/131/problem/C (3) //[EASY][BRUTE-FORCE][COMB-NUMBERS]

http://codeforces.com/contest/131/problem/B (2) //[EASY]

http://codeforces.com/contest/129/problem/E (5) //[NICE][COMB-NUMBERS]//Observe

http://codeforces.com/contest/111/problem/D (5) //[COMB-NUMBERS][POWER][VERY NICE][DP]

http://codeforces.com/contest/895/problem/D (4) //[COMB-NUMBERS][OPTI]

http://codeforces.com/contest/893/problem/E (5) //[COMB-NUMBERS][NUMBER-THEORY]

http://codeforces.com/contest/894/problem/B (3) //try without last row

http://codeforces.com/contest/890/problem/E (6) //Permutations

http://codeforces.com/contest/52/problem/B (4) //[NICE][PREPROCESS][ROTATION]

3917 //Grid tiling [fancy approximation fomula]

http://codeforces.com/contest/760/problem/F

https://devskill.com/CodingProblems/ViewProblem/61

https://devskill.com/CodingProblems/ViewProblem/255

UVA 10918

UVA 12576

UVA 1118 //Parity

http://www.spoj.com/problems/HLP_RAMS/ //Comb parity

Project Euler #78: Coin partitions //Partition function

http://www.spoj.com/problems/MAIN75/ //DP #of trees

12001 UVA (3)

12034 UVA (4)

11719 UVA (5)

11798 UVA (5)

11282 UVA (4) //dearrangement

11174 UVA (4)

http://codeforces.com/contest/666/problem/C 7

http://www.spoj.com/problems/JOKER1/ 3 prod(Ai-i)

http://www.spoj.com/problems/ANTP/ //4

http://codeforces.com/contest/645/problem/E (5) //formula: A[i]=Sum(A)+1

http://www.spoj.com/problems/SPCE/ (5) // N^{K-2}*Prod(comp_size)

http://codeforces.com/contest/785/problem/D (5) // F'(' C"(+)-1","("

13184 UVA (3)

http://codeforces.com/contest/816/problem/D (5) // Observation

13214 (4) //OEIS? : C(N+M-2,N-1)

http://codeforces.com/contest/844/problem/B (2) //Easy — pro prvaky

http://www.spoj.com/problems/JOSWAP/ (3) //Frequence array

http://www.spoj.com/problems/UCV2013E/ (4) //NICE&EASY: Choose steps to direction

http://www.spoj.com/problems/PARCARD1/ (4) //Partition function (raw)

http://www.spoj.com/problems/GOODB/ (2) //Easy (NICE): Choose [order]

http://www.spoj.com/problems/LOOPEXP/ (4) //A000254/N!

http://www.spoj.com/problems/DTPOLY/ (5) //DP might work too

http://www.spoj.com/problems/DTPOLY2/ (7) //Harder version of above (NICE but hell)

http://www.spoj.com/problems/HC12/ (3) //NICE — Sort + C(i,K-1)*A[i]

http://www.spoj.com/problems/STONE2/ (4) //NICE — Mostly DP [INVERSION][FACTORIAL]

http://www.spoj.com/problems/MAIN8_D/ (5) //NICE — Suffixes/Prefixes (same add 2^i)

http://www.spoj.com/problems/ITRIX_E/ (4) //VERY NICE — #Nonattacking 2-queens

http://www.spoj.com/problems/MAXSUB/ (3) //NICE — Subsets made of zeroes

http://www.spoj.com/problems/SKYLINE/ (3) //Catalan numbers [weird modulo — care]

http://codeforces.com/contest/26/problem/D (5) //Division of two combintion numbers [NI:/]

http://codeforces.com/contest/872/problem/E (6) // Prod:Sum(C(DistLines,CompSize))

https://codeforces.com/contest/1174/problem/C (4) //[VERY NICE][SIEVE]

https://codeforces.com/contest/1173/problem/B (3) //[VERY NICE][MATH]

https://codeforces.com/contest/1202/problem/D (4) //[NICE][MATH][GREEDY]

https://codeforces.com/contest/1199/problem/E (5) //[VERY NICE!][OBSERVATION][DFS]

https://codeforces.com/contest/1180/problem/D (5) //[VERY NICE][OVSERVATION]

https://codeforces.com/contest/1178/problem/D (4) //[VERY NICE][OBSERVATION][NUMBER THEORY]

https://codeforces.com/contest/1187/problem/C (4) //[NICE][IMPLEMENTATION]

http://codeforces.com/contest/922/problem/F (6) //[NICE][MATH][GREEDY]

http://codeforces.com/contest/916/problem/C (3) //Graph construction

http://codeforces.com/contest/148/problem/B (3) //[SIMULATION](math or bs)

http://codeforces.com/contest/909/problem/F (6) //[VERY NICE][BITS]

http://codeforces.com/contest/141/problem/C (4) //[NICE][BRUTE-FORCE]

http://codeforces.com/contest/907/problem/D (5) //[VERY NICE][RANDOM]

http://codeforces.com/contest/124/problem/C (3) //[NICE][SIEVE]

http://codeforces.com/contest/125/problem/C (4) //[NICE][C(N,2)]

http://codeforces.com/contest/902/problem/C (4) //[NICE]//Tree isomorphism

http://codeforces.com/contest/112/problem/C (3) //[GREEDY]//Max + 1s

http://codeforces.com/contest/110/problem/B (2) //Easy modulo

http://codeforces.com/contest/894/problem/C (3) //[VERY NICE] //AiAiGCD

http://codeforces.com/contest/97/problem/B (4) //NICE — Walls in middles [D&C]

http://codeforces.com/contest/85/problem/A (3) //MODULO / SHIFT

http://codeforces.com/contest/81/problem/D (3) //NICE — MAX(N/2) — even/odd

http://codeforces.com/contest/63/problem/D (3) //NICE[GO BY LINES][4 WAYS B/D ODD/EVEN]

http://codeforces.com/contest/42/problem/C (4) //Constructive works too but random is fine :)

http://codeforces.com/contest/43/problem/D (3) //NICE — Easy to see [implementation]

http://codeforces.com/contest/53/problem/C (2) //EASY [B/E Alternate]

http://codeforces.com/contest/877/problem/C (3) //NICE 3*Alternative

http://codeforces.com/contest/802/problem/H (6) //We can do "N+k" by adding a letter p+k*x+u+xx

http://codeforces.com/contest/12/problem/E (5) //g[i][j]=1+(i+j)%(N-1) [+/-]

http://codeforces.com/contest/22/problem/C (4) //Start and then clique without v (+ random)

http://codeforces.com/contest/26/problem/C (5) //make Even*Even: do by 2*2 fields

http://codeforces.com/contest/41/problem/E (4) //[NICE][CN/2,N/2]

http://codeforces.com/contest/78/problem/B (2) //NICE — last 3 and then rest in modulo

http://codeforces.com/contest/109/problem/D (5) //[NICE][BACK-POINTERS][SIMULATION][SORT]

http://www.spoj.com/problems/ADASEA/

https://codeforces.com/contest/1176/problem/E (4) //[NICE][CONSTRUCTIVE][TREE][TOPO]

https://codeforces.com/contest/1186/problem/F (5) //[NICE][GREEDY][CONSTRUCTIVE]

https://codeforces.com/contest/1189/problem/D2 (5) //[NICE][CONSTRUCTIVE]

https://atcoder.jp/contests/agc035/tasks/agc035_b (4) //[NICE][DIRECTION]

https://www.spoj.com/problems/CHUNK2/ (3) //[DFS][PRIMES]

https://codeforces.com/gym/101981 K //[VERY NICE][IMPLE][TREE][SIMULATION]

https://www.urionlinejudge.com.br/judge/en/problems/view/1621 (4) //[TREE][IMPLE]

https://www.urionlinejudge.com.br/judge/en/problems/view/1610 (3) //[CYCLE]

https://www.urionlinejudge.com.br/judge/en/problems/view/2911 (4) //[NICE][RULES][SIMPLE]

https://codeforces.com/gym/102001/problem/K (4) //[VERY NICE]

https://codeforces.com/gym/101972/problem/B (6) //[VERY NICE][TREE][STL]

https://toph.co/p/incompatible-crops (2)

http://codeforces.com/gym/100112 K //[NICE][BS][COLORING]

http://codeforces.com/gym/101962 D //[NICE] //Bitset shall work too

4286 — Equilibrium Mobile LA //[VERY NICE][OBSERVATION][TREE][DP]

http://codeforces.com/gym/101801 (4) [H] //[TREE][DP] //More dfss

https://www.urionlinejudge.com.br/judge/en/problems/view/2732 (3) //Easy flood

http://codeforces.com/contest/920/problem/E (5) //[NICE][DFS][SET] //Or clever random

http://codeforces.com/contest/915/problem/D (4) //[VERY NICE][CYCLES DETECTION (ORIENTED)]

http://www.spoj.com/problems/CTTC/ (3) //[EASY][GRAPH-RECONSTRUCTION]

7951 — Islands (3) //[NICE]Flood-Fill

http://codeforces.com/contest/901/problem/D (7) //Observations / Tree reduction

http://codeforces.com/contest/902/problem/B (3) //No dfs needed

http://codeforces.com/gym/101630 {C}(4) //[NICE][SCC]

http://codeforces.com/gym/101620 {J}(4) //DFS + multiples of divisors

http://codeforces.com/contest/120/problem/F (3) //Width of tree

7606 — Percolation (3) //Dfs on grid [EASY]

http://codeforces.com/contest/116/problem/C (2) //[DEPTH]

8080 — Christmas Tree (3) //[SIMPLE][NICE]

6584 — Escape (8) //[VERY VERY VERY NICE][COMPRESSION][MERGING] //Hard but I recommend this one!!

6590 Digraphs (4) //[VERY NICE][CYCLES][DP][IDEA]

http://codeforces.com/contest/893/problem/C (3) //Minimum from each connected component

http://codeforces.com/contest/884/problem/C (3) //[EASY][PERMUTATIONS][SORTING]

http://codeforces.com/contest/883/problem/G (4) //Greedy picking

http://codeforces.com/contest/60/problem/B (3) //3D Flood-Fill [NICE][EASY]

http://codeforces.com/contest/60/problem/C (4) //[VERY NICE][BF]//Not many real possibilities

https://devskill.com/CodingProblems/ViewProblem/3

https://devskill.com/CodingProblems/ViewProblem/17

https://devskill.com/CodingProblems/ViewProblem/118 //Kind-of

657 — The die is cast [UVA]

12186 UVA (3)

http://codeforces.com/contest/734/problem/E (5)

http://codeforces.com/contest/727/problem/A (3)

http://codeforces.com/contest/723/problem/E (6)

http://codeforces.com/contest/709/problem/E (6)

http://codeforces.com/contest/710/problem/E (4)

http://codeforces.com/contest/758/problem/E (8)

11323 UVA (5)

http://codeforces.com/contest/760/problem/B (3)

http://codeforces.com/contest/761/problem/E (6)

http://codeforces.com/contest/638/problem/B (3) //connect cons. letters

http://codeforces.com/contest/638/problem/C (4) //greedy idea — easy

http://codeforces.com/contest/638/problem/D (5) //spec-DAG articulatin

http://codeforces.com/contest/767/problem/C (4)

http://codeforces.com/contest/781/problem/C (5)

http://codeforces.com/contest/794/problem/D (5) //NICE! Right done dfs

http://codeforces.com/contest/802/problem/K (5) //Slightly DP-like (NICE) TREE

http://codeforces.com/contest/813/problem/C (3) //Simply 2 DFS: NICE + EASY

http://codeforces.com/contest/841/problem/D (4) //DFS while tracking "next"

http://codeforces.com/contest/845/problem/G (5) //Keep track of cycles

http://codeforces.com/contest/844/problem/E (5) //Post-Order → line, Connect i → N-2: star

http://www.spoj.com/problems/CAC/ (5) //VERY NICE! — Find all cycles in cactus

http://codeforces.com/contest/849/problem/C (3) //State search by gauss

http://codeforces.com/contest/846/problem/E (5) //NICE: DFS + some overflow logic

http://www.spoj.com/problems/KOZE/ (3) //NICE: Floods

http://www.spoj.com/problems/RIOI_2_3/ (4) //DFS /OR/ BFS /OR/ DSU [NICE][EASY][BF]

http://www.spoj.com/problems/MAKEMAZE/ (3) //EASY — Simple dfs on grid

http://codeforces.com/contest/861/problem/F (5) //VERY NICE: Modify dfs tree so it remains connected

http://www.spoj.com/problems/GHOSTS/ (3) //NICE — must remain dag after each QR

http://www.spoj.com/problems/AMR10J/ (5) //VERY NICE! — DFS+DP [DAG with cycles]

http://codeforces.com/contest/24/problem/A (2)//NICE [DFS-ON-CYCLE]

http://codeforces.com/contest/29/problem/C (3) //Find begining/end of line (graph)

http://codeforces.com/contest/29/problem/D (4) //Tree [implementation][simulation]

https://devskill.com/CodingProblems/ViewProblem/564 (2) //[OBSERVATION]

http://www.spoj.com/problems/PR003004/ (4) //Simple digits count

http://codeforces.com/contest/770/problem/B (3) //max num max digsum

http://www.spoj.com/problems/ADATRIP/

https://www.urionlinejudge.com.br/judge/en/problems/view/1655 (4) //[EASY][PROBABILITY]

https://www.urionlinejudge.com.br/judge/en/problems/view/2910 (4) //[TREE]

http://codeforces.com/gym/101628/problem/f (4)

http://codeforces.com/gym/100112 E //[NICE][BS][GEOMETRY]

http://codeforces.com/gym/101845/problem/J (5) //[NICE][OBSERVATION][TWICE]

http://codeforces.com/gym/101801 K //[NICE][MULTIPLE NODES]

http://codeforces.com/gym/101879/problem/F (8) //[NICE][BRIDGE]

http://codeforces.com/gym/101666 D //[NICE]

http://codeforces.com/contest/144/problem/D (4) //[VERY NICE][IFS]

http://www.spoj.com/problems/ADRABR/ (3) //Classical dijkstra — bad statement

http://codeforces.com/contest/141/problem/D (5) //[NICE]Many Conditions

6583 Subway (5) //[NICE]//Not exactly dijkstra by slightly similar [IMPLEMENTATION]

3850 [LA]

Gym 100625D [2013 Benelux Algorithm Programming Contest (BAPC 13)]

UVA 12950

Gym 100753A [2015 German Collegiate Programming Contest (GCPC 15) + POI 10-T3]

UVA 13030

UVA 1027

UVA 11377

http://codeforces.com/problemset/problem/843/D

11813 UVA

Gym 101242B [2016 ACM-ICPC World Finals] //+DP

Gym 100923B [2015 ACM National Contest Romania — Round 1]

UVA 11833

http://www.spoj.com/problems/EZDIJKST/en/

LightOJ 1019

UVA 13010 //+TS

2819 [LA]

UVA 12144

http://codeforces.com/contest/716/problem/D 7

12047 UVA 4

11514 UVA 4

http://codeforces.com/contest/757/problem/F 7

11338 UVA (4)

11374 UVA (4)

11097 UVA (4) //Divide to N*1000 nodes and go!

13172 UVA (5) //6*DJ per query + permutations

10816 UVA (4) //Easy Linear-Search by answer + DJ with path

http://codeforces.com/contest/827/problem/F 7 //Very nice — Even&Odd

http://www.spoj.com/problems/DELIVER/ (5) //Normalize coordinates + Optimalize

http://www.spoj.com/problems/CCHESS/ (4) //Dijkstra as knight

https://codeforces.com/contest/1175/problem/F (7) //[VERY NICE][HASH][RANDOMISATION]

https://codeforces.com/contest/1181/problem/E2 (7) //[VERY NICE][SORTING][ST]

https://codeforces.com/contest/1181/problem/E1 (5) //[VERY NICE][OBSERVATION][SORTING]

https://codeforces.com/gym/102058/problem/G (7) //[VERY NICE][BS][PRIORITY_Q]

http://codeforces.com/gym/101845/problem/L (6) //[VERY NICE][INDUCTION]

http://codeforces.com/gym/101801 J //[NICE][TRIE][RMQ]

8257 — Factor-Free Tree LA //[VERY VERY NICE][PRIMES][FACTOR]

https://www.urionlinejudge.com.br/judge/en/problems/view/1683 (4) //RAW histogram

http://codeforces.com/contest/817/problem/D (5) //Very nice NlogN

http://www.spoj.com/problems/DYNACON2/ (8) //Lesser hell — offline Nlog(N) /or/ NlogN^2

http://codeforces.com/contest/876/problem/F (5) //VERY NICE — Find greatest + next/back functions

https://codeforces.com/contest/1176/problem/D (4) //[NICE][GREEDY][SORTING]

https://atcoder.jp/contests/abc136/tasks/abc136_e (5) //[NICE][GREEDY][DIVISORS]

https://codeforces.com/contest/1183/problem/F (5) //[VERY NICE][SORTING][OBSERVATION][BF]

https://www.spoj.com/problems/KPOWERSUM/ (4) //[FACTORISATION]

http://codeforces.com/gym/101992/problem/D (5) //[VERY NICE][IE][NUMBER THEORY]

http://codeforces.com/gym/101982 B //[FACTORISATION][GCD][SIEVE]

http://codeforces.com/gym/101864 G //[VERY NICE][FACTORISATION][GCD]

http://codeforces.com/gym/101840 D //[EVENTS][NICE]

http://codeforces.com/gym/101741/problem/F (6) //[NICE][PROBABILITY][GCD]

http://www.spoj.com/problems/FRNDAM/ (3) //Simply find sum of all divisors (low constraints)

http://codeforces.com/contest/920/problem/F (5) //[NICE][FAST FALL][SET][DIVISORS]

7726 A Simple Math Problem (4) //TLE if naive (consider only divisors)

http://codeforces.com/contest/112/problem/D (4) //[NICE] Last-position [FACTOR]

http://codeforces.com/contest/75/problem/C (3) //[NICE][BS]

LightOJ 1068

LightOJ 1134

Project Euler #95: Amicable chains

NAJ0001 — Divisible Number Sum [SPOJ]

http://www.spoj.com/problems/LCMSUM/

https://www.hackerrank.com/contests/101hack38/challenges/easy-gcd-1/problem

UVA 13085

http://www.spoj.com/problems/CDRSANJ/

http://www.spoj.com/problems/DIVSEQ/

UVA 12154

UVA 13058

http://www.spoj.com/problems/EC_DIVS/

https://www.codechef.com/problems/CHEFKEY

http://codeforces.com/problemset/problem/671/C

Gym 101411G [2009-2010 ACM-ICPC, NEERC, Western Subregional Contest]

http://codeforces.com/problemset/problem/831/F

http://codeforces.com/problemset/problem/839/D

12934 — Factorial Division [UVA]

UVA 10880

http://www.spoj.com/problems/PSTR/

http://codeforces.com/problemset/problem/27/E

[LA] 3014

UVA 12843

https://www.urionlinejudge.com.br/judge/en/problems/view/1164

http://codeforces.com/problemset/problem/803/F

10892 — LCM Cardinality

http://www.spoj.com/problems/GCDEX/

http://www.spoj.com/problems/INVDIV/

13083 — Yet another GCDSUM //ll

http://www.spoj.com/problems/IITKWPCF/ //ll

UVA 13185

UVA 13194

UVA 11388

http://www.spoj.com/problems/SAS002/

12425 — Best Friend

http://codeforces.com/problemset/problem/703/E

https://www.hackerearth.com/problem/algorithm/harry-gets-into-infy/

UVA 10830 //SUM

http://www.spoj.com/problems/DIVSUM/en/ //SUM

http://www.spoj.com/problems/AFS/ //SUM

UVA 11526 //SUM

http://www.spoj.com/problems/ADAZOO/

http://www.spoj.com/problems/ADASEQEN/

http://www.spoj.com/problems/ADAMOLD/

http://www.spoj.com/problems/ADASALE/

https://codeforces.com/contest/1203/problem/F2 (6) //[VERY NICE][GREEDY][SORTING][CASES]

https://codeforces.com/contest/1176/problem/F (5) //[NICE][IMPLE][SORTING]

https://codeforces.com/contest/1200/problem/F (6) //[NICE][DFS][GRAPH][LCM][MATH]

https://codeforces.com/contest/1201/problem/D (5) //[NICE][DP][IMPLE][CASES]

https://www.spoj.com/problems/THECODE/ (4) //[BITMASK]

https://codeforces.com/contest/1199/problem/F (5) //[NICE][DIMENSIONS]

https://codeforces.com/contest/1183/problem/H (4) //[NICE][SUBSEQUENCE][NEXT]

https://codeforces.com/contest/1183/problem/E (4) //[NICE][SUBSEQUENCE][NEXT]

https://codeforces.com/contest/1178/problem/F2 (7) //[VERY NICE][OBSERVATION]

https://codeforces.com/contest/1178/problem/F1 (5) //[NICE][MATH][REDUCTION]

https://codeforces.com/contest/1178/problem/B (3) //[EASY]Not even real DP

https://codeforces.com/contest/1195/problem/C (3) //[EASY]

https://codeforces.com/contest/1189/problem/F (6) //[VERY NICE][OBSERVATION]

https://atcoder.jp/contests/agc035/tasks/agc035_d (5) //[VERY NICE][BIT][IDEA]

https://www.spoj.com/problems/PLOVER/ (4) //[NICE][DIGITS]

https://www.spoj.com/problems/NICESEQ/ (4) //[DIGITS][POSSIBLY FASTER]

https://codeforces.com/gym/101981 L //[NICE]

https://www.spoj.com/problems/RANDMOD/ (4) //[OBSERVATION][SEQUENCE]

https://www.urionlinejudge.com.br/judge/en/problems/view/1592 (4) //[GRAPH]

https://www.urionlinejudge.com.br/judge/en/problems/view/2824 (4) //Classical

https://codeforces.com/gym/102006/problem/D (4) //[NICE][OBSERVATION]

https://codeforces.com/gym/102021 K

https://codeforces.com/gym/102058/problem/D (5) //[NICE][DOMINATION]

UVA 13294 (4) //[BIT]

http://codeforces.com/gym/101992/problem/A (6) //[BITS][OBSERVATION]

http://codeforces.com/gym/101628/problem/H (3) //[NICE][CLASSICAL][DAG]

http://codeforces.com/gym/101628/problem/A (3)

http://codeforces.com/gym/100112 J //[NICE][TREE]

http://codeforces.com/gym/101982 D //[VERY NICE][BITS] //Window

http://codeforces.com/gym/101982 C //Classical combinatorics

http://codeforces.com/gym/101845/problem/E (5)

https://www.codechef.com/problems/SPECTAC (5) //[NICE]

http://codeforces.com/gym/101801 [E]

http://codeforces.com/gym/101801 D //[VERY NICE][SEGMENT TREE][SORTING][NORMALIZE]

http://codeforces.com/gym/101873 J //[NICE][IMPLEMENTATION][STRING][SUBSUBSET]

http://codeforces.com/gym/101889 E

http://codeforces.com/gym/101808/problem/D (7) //[NICE][OPTIMISATION][EFFICIENCY]

http://codeforces.com/gym/101666 I

http://codeforces.com/gym/101840 A //Doubles

DevSkills 475: Bunty's Xor Game (4) //[BITS][GAME THEORY]

https://www.devskill.com/CodingProblems/ViewProblem/489 (5) //[NICE][FACTORISATION]

DevSkills 534 (4) //[BITSET][COMBINATIONS]

http://codeforces.com/gym/101650 D //Not hard — more coding + printing

13286 — Ingredients (4) //[NICE][DAG] Classical

8299 — Bricks (5) //[NICE][COMBINATORICS][SORTING]

http://codeforces.com/contest/934/my (4) //Subsequence

http://codeforces.com/contest/922/problem/E (5) //find max mana

http://codeforces.com/contest/920/problem/D (4) //[NICE][KNAPSACK-MODULO][GREEDY]

http://codeforces.com/contest/919/problem/D (4) //[NICE][DFS][CYCLE][DAG]

http://codeforces.com/contest/914/problem/C (3) //[DIGITS][BINARY]

http://codeforces.com/contest/913/problem/E (5) //[NICE][EXPRESSION]

http://codeforces.com/contest/148/problem/E (5) //[DP][PREFIX SUM][GREED]

http://www.spoj.com/problems/PALMKR/ (4) //Classical palindrome + print + lexicography

http://codeforces.com/contest/146/problem/E (5) //[NICE][COMBINATORICS][OBSERVATION]

http://codeforces.com/contest/909/problem/C (4) //[NICE][CLASSICAL][EASY]

7785 — m-ary Partitions (4) //Combinatorics

http://codeforces.com/contest/133/problem/E (4) //[IMPLEMENTATION]

http://codeforces.com/contest/126/problem/D (5) //[NICE]//Decomposet DP//Own hash-map

http://codeforces.com/contest/910/problem/B (3) //Or many other ways

6154 RNA Secondary Structure (5) //[NICE] Unoptimal might work too

https://arc087.contest.atcoder.jp/tasks/arc087_b (4) //[VERY NICE][OBSERVATION]

http://codeforces.com/contest/903/problem/F (5) //[VERY NICE][BITMASK][BRUTE]

http://codeforces.com/contest/903/problem/A (2) //Easy knapsack-like // Low constraints

http://codeforces.com/contest/900/problem/E (4) //[NICE]//Patter-match: FFT or KMP or Brute-Force

http://codeforces.com/contest/118/problem/D (3) //[COMBINATORICS][LOW-CONSTRAINTS]

http://codeforces.com/contest/115/problem/E (5) //[VERY NICE][SEGMENT TREE]

http://codeforces.com/contest/116/problem/D (3) //CLASSICAL[LOW-CONSTRAINTS]

10128 Queue (uva) (4) //One possibility is bitmask — second combinatorics

http://codeforces.com/contest/110/problem/C (3) //[EASY]// Greedy/math works too

8078 — Bracket Sequence (4) //[VERY NICE][DP-LINKS]

http://codeforces.com/contest/106/problem/C (3) //[NICE][EASY]

http://codeforces.com/contest/895/problem/C (4) //[NICE]

8024 Stack Construction (4) //[NICE] Palindromic style — but not exactly

7708 — Cubes (6) //[MATH]

http://codeforces.com/contest/888/problem/F (6) //[NICE][FLAG]

http://www.spoj.com/problems/ACQUIRE/ (5) //[NICE][CH-OPT]

http://codeforces.com/contest/319/problem/C (6) //[NICE][CH-OPT]

http://www.spoj.com/problems/NKLEAVES/ (5) //[NICE][DC]

http://codeforces.com/contest/76/problem/D (4) //[BITS][OVERFLOW]

http://codeforces.com/contest/73/problem/C (4) //[NICE][EASY][TRY-ALL-LETTERS]

http://codeforces.com/contest/67/problem/C (4) //[NICE][LEAVENSTEIN]

http://codeforces.com/contest/67/problem/A (3) //[EASY][PRINTING][OTHER POSSIBLE WAYS]

http://codeforces.com/contest/55/problem/D (5) //[NICE][DIGITS][EFFICIENT]

http://codeforces.com/contest/56/problem/D (4) //String modification + printing [NICE]

http://codeforces.com/contest/58/problem/E (6) //[NICE][IMPLEMENTATION]

UVA 12181

https://devskill.com/CodingProblems/ViewProblem/21

https://devskill.com/CodingProblems/ViewProblem/37

https://devskill.com/CodingProblems/ViewProblem/71

https://devskill.com/CodingProblems/ViewProblem/103

https://devskill.com/CodingProblems/ViewProblem/107

https://devskill.com/CodingProblems/ViewProblem/115

https://devskill.com/CodingProblems/ViewProblem/126

https://devskill.com/CodingProblems/ViewProblem/131

https://devskill.com/CodingProblems/ViewProblem/134

https://devskill.com/CodingProblems/ViewProblem/174

https://devskill.com/CodingProblems/ViewProblem/186

https://devskill.com/CodingProblems/ViewProblem/201

https://devskill.com/CodingProblems/ViewProblem/338

https://devskill.com/CodingProblems/ViewProblem/368

https://devskill.com/CodingProblems/ViewProblem/392

https://devskill.com/CodingProblems/ViewProblem/399

https://www.hackerrank.com/contests/world-codesprint-5/challenges/mining //Opti

UVA 12915 //Opti

UVA 12524 //Opti

http://codeforces.com/problemset/problem/631/E //CH

https://devskill.com/CodingProblems/ViewProblem/6

https://devskill.com/CodingProblems/ViewProblem/11

11552 UVA (3)

12172 UVA (3)

4507 LA (5)

4510 LA (5) [+ geometry]

12181 UVA (6)

http://codeforces.com/contest/729/problem/F 6

http://codeforces.com/contest/735/problem/E 9

http://codeforces.com/contest/731/problem/E 5

12030 UVA (4)

http://codeforces.com/contest/721/problem/E 7

http://codeforces.com/contest/742/problem/D 4

12040 UVA (5)

http://codeforces.com/contest/712/problem/D 5

13162 UVA (6)

http://codeforces.com/contest/743/problem/E 6

11908 UVA (3)

11932 UVA (4)

http://codeforces.com/contest/745/problem/E (7)

11806 UVA (4)

http://codeforces.com/contest/747/problem/F (5)

11843 UVA (4)

http://codeforces.com/contest/752/problem/E (5)

http://codeforces.com/contest/703/problem/E (7)

11753 UVA (4)

11725 UVA (5)

http://codeforces.com/contest/722/problem/E (9)

http://codeforces.com/contest/760/problem/F (8)

11795 UVA (3)

11654 UVA (4)

11523 UVA (5)

11404 UVA (4)

11432 UVA (4)

11451 UVA (4) //C==20 mistake in statement

11301 UVA (4)

http://codeforces.com/contest/762/problem/D 5

11361 UVA (4) //digit DP

11365 UVA (7)

11391 UVA (4) //easy+implementation

11394 UVA (3)

11218 UVA (2)

11125 UVA (4) //slightly implementation

11076 UVA (3)

11081 UVA (4) //3 string subsequences (beware of fail)

http://codeforces.com/contest/678/problem/E (5) //bitset dp + probability

http://codeforces.com/contest/766/problem/C (4)

http://codeforces.com/contest/667/problem/C (3)

http://www.spoj.com/problems/MOVIFAN/ (3)

http://www.spoj.com/problems/ORDSUM23/ (3)

http://www.spoj.com/problems/DIVSEQ/ (4) //N^3 (but better...) works fine

http://codeforces.com/contest/633/problem/F (7) //Tree dp

http://www.spoj.com/problems/ADJDUCKS/ (4) sort + pick 2-3 continous O(N)

http://www.spoj.com/problems/JLNT/ (4) //pick 0 or 2 | 1e3*5e3

http://www.spoj.com/problems/TPCPALIN/ (5) //500^3 works (3rd countable)

http://www.spoj.com/problems/COLORSEG/ (4) //50^4==OK 50^4log(N)=TLE NICE

http://www.spoj.com/problems/POWERCAR/ (3) //1e3*1e3*2 — follow rules

http://www.spoj.com/problems/INGRED/ (5) //TSP-like [reduce + go]

http://www.spoj.com/problems/BADXOR/ (4) //classical subsets

http://www.spoj.com/problems/SPCO/ (5) //64*64*2 DP {OPT: prime O(1) + clear only half}

http://www.spoj.com/problems/WAYHOME/ (5) //NICE: 1) 1*1 b)12,1,**,2

http://www.spoj.com/problems/NFURY/ (2) //Minimal sum of squares

http://www.spoj.com/problems/GDIL/ (3) //combinatorics

http://codeforces.com/contest/791/problem/D (5) //Tree

http://codeforces.com/contest/791/problem/E (6) //V,K,X — pick any

http://codeforces.com/contest/789/problem/C (3)

13176 (4) //N^6

13179 (5) //NICE [Ath][Bth][TimeDiff]

http://codeforces.com/contest/796/problem/E (6) //NICE: N*P*K*K (WC can't happen!)

http://codeforces.com/contest/797/problem/E (4) //NICE: Almost BF-able (but care of low K)

http://codeforces.com/contest/793/problem/D (3) //NICE & EASY: begin/end/actual/USED

http://codeforces.com/contest/803/problem/E (4) //State search — many IF's (EASY)

http://codeforces.com/contest/805/problem/F (7) //NICE: DP on tree + fast BF + hack

http://codeforces.com/contest/808/problem/E (5) //NICE!

http://codeforces.com/contest/811/problem/C (4) //Precalculate + DP (greedy thinking)

10817 UVA 4 //Easy but slightly implementation

10859 UVA 4 //Nice — on tree .. but for a reason small constrains

10898 UVA 4 //Hash is lesser than 1e6 .. try everything

http://codeforces.com/contest/812/problem/B (3) //Not only DP, yet imho easiest ..many spec cases

http://codeforces.com/contest/813/problem/D (5) //VERY VERY NICE — N*N (none picked between a/b)

http://codeforces.com/contest/814/problem/E 5 //VERY NICE — Harder imple: Combinatorics

http://codeforces.com/problemset/problem/816/E (6) //NICE — Tree (hard 2C complexity)

http://codeforces.com/contest/837/problem/D (5) //NICE — yet kinda pain [must be iterative]

http://www.spoj.com/problems/AUT/ (4) //NICE — K is interesting ~ at most 1600

http://www.spoj.com/problems/GNYR04C/ (3) //Easy — Nice idea [Big→ Low approach]

http://www.spoj.com/problems/TIEROPE/ (4) //Process 2*L ~ otherwise pick BIG

http://www.spoj.com/problems/IITKWPCE/ (4) //Palindromes [efficiency!] — NICE!

IITKWPCD SPOJ (4) //+Slightly geometry

UVA 1496 //[Steiner's Tree] Very Nice (8)

http://www.spoj.com/problems/LKS/ (3) //Classical knapsack

http://www.spoj.com/problems/UOFTAE/ (3) //Easy & Sympatic DP

http://www.spoj.com/problems/DCOWS/ (4) //Very NICE (sort + GO)

http://www.spoj.com/problems/FARIDA/ (3) //Easy & Sympatic ((u+1) | Price+(u+2))

http://www.spoj.com/problems/AU7_5/ (2) //EASY: dyn(n-1)+dyn(n-k-1)

http://www.spoj.com/problems/NAIVELOK/ (4) //NICE [depalindromisation]

http://codeforces.com/contest/846/problem/C (4) //With print

http://www.spoj.com/problems/CNT_LUCK/ (4) //Number (binary) dp [NICE] {ull care 0-1}

http://www.spoj.com/problems/MAY99_4/ (3) //Almost combinatoric Sub and 0/1,1/0

http://www.spoj.com/problems/GEEKOUNT/ (4) //Number dp

http://www.spoj.com/problems/MUTDNA/ (4) // N*2 (turned?) [not sure if grd poss.]

http://www.spoj.com/problems/RIOI_3_2/ (5) //VERY NICE (easy imple — Number Theory thinking)

http://www.spoj.com/problems/MAXWOODS/ (3) //NICE [EASY][GRID]

http://www.spoj.com/problems/DIEHARD/ (3) //Easy — prolly solvable by greedy (but dp is easier)

http://www.spoj.com/problems/DCEPC810/ (4) //VERY VERY NICE — Subsequence 2pointers+2bools

http://www.spoj.com/problems/EQ2/ (4) //NICE: Digit + Carry (from back) — iff-party

http://www.spoj.com/problems/DCEPC501/ (3) //NICE & EASY

http://www.spoj.com/problems/NUMTSN/ (4) //NICE — Thinking or Opti

http://www.spoj.com/problems/GONE/ (4) //NICE & EASY [digits]

http://www.spoj.com/problems/RAONE/ (4) //NICE & EASY [digits] — almost similar as above

http://www.spoj.com/problems/STRSEQ/ (4) //VERY VERY NICE — Next-Function

http://www.spoj.com/problems/MYQ8/ (4) //VERY NICE — 3x3 tic-tac-toe [implementation]

http://codeforces.com/contest/859/problem/C (3) //Easy+Sympathic [PrefixSumOptional]

http://codeforces.com/contest/859/problem/D (4) //NICE [Probabilities]

http://www.spoj.com/problems/UNICA/ (4) //VERY NICE [Posibilities][Print][Classical]

http://www.spoj.com/problems/KOPC12H/ (4) //NICE Digit-DP

http://www.spoj.com/problems/DRACULA/ (4) //NICE Digit-DP (Both sides) — iterate by sum

http://www.spoj.com/problems/ABCPATH/ (3) //DP over dfs (maybe without dp works too?)

http://www.spoj.com/problems/BEHAPPY/ (2) //Easy one — low constraints

http://www.spoj.com/problems/STRCOUNT/ (4) //No input (over bits)

http://codeforces.com/contest/855/problem/B (2) //prolly not even necessary

http://codeforces.com/contest/855/problem/C (4) //dp on tree

http://codeforces.com/contest/855/problem/E (5) //VERY NICE — Digits & Bitmask & Query (learning!)

http://www.spoj.com/problems/PAINTWAL/ (6) //VERY NICE — Imho hard (opti could beat)

http://www.spoj.com/problems/ADFRUITS/ (3) //Very simple (substring == subsequence)

http://www.spoj.com/problems/MAIN113/ (2) //NICE but somehow too low constraints

http://www.spoj.com/problems/MAIN112/ (4) //NICE — Bitmask

http://codeforces.com/contest/864/problem/E (5) //VERY NICE — Sort

http://www.spoj.com/problems/NOVICE63/ (4) //NICE -On digits (binary)

http://www.spoj.com/problems/TUG/ (3) //NICE + Observation {N>100 == YES}

http://www.spoj.com/problems/DOMINO1/ (4) //Used map to solve it

http://www.spoj.com/problems/NY10E/ (2) //Easy dp

http://www.spoj.com/problems/MAIN72/ (3) //Easy knapsack

http://www.spoj.com/problems/NOVICE43/ (2) //Unbelievably low constraints

http://codeforces.com/contest/598/problem/E (4) //N^5 strategy works fine [VERY NICE]

http://www.spoj.com/problems/CHAIR/ (3) //Maybe combinatorics too?

http://www.spoj.com/problems/ACPC10D/ (3) //NICE — DAG traversal

http://www.spoj.com/problems/CPCRC1C/ (4) //Digits dp (return pair)

http://www.spoj.com/problems/BORW/ (3) //Inc+Dec sequence (small array)

http://codeforces.com/problemset/problem/16/E (5) //Bitmask [NICE]

http://codeforces.com/problemset/problem/18/E (5) //VERY NICE {no need for second iteration}

http://codeforces.com/contest/2/problem/B (5) //NICE — 2/5 are in-fact independent

http://codeforces.com/contest/4/problem/D (3) //Classical [FW works too] XY > xy

http://codeforces.com/contest/6/problem/D (4) //NICE (N^4)

http://codeforces.com/contest/321/problem/E (7) //VERY NICE — D&C Trick

http://codeforces.com/contest/868/problem/F (8) //VERY VERY NICE D&C Trick — With MO Principal

http://codeforces.com/contest/8/problem/C (5) //NICE — Masks [N*2^N]

http://codeforces.com/contest/868/problem/E (8) //VERY NICE — HARD — on tree

http://codeforces.com/contest/10/problem/D (4) //LCIS [NICE]

http://codeforces.com/contest/13/problem/C (5) //NICE [sorting][only elements from array]

http://codeforces.com/contest/17/problem/C (5) //[NICE][iterative-sparse][+idea]

http://codeforces.com/contest/19/problem/B (4) //Knapsack (after good look)

http://codeforces.com/contest/30/problem/C (4) //Probabilities + (slight)GEO

http://codeforces.com/contest/31/problem/E (4) //[NICE]

http://codeforces.com/contest/41/problem/D (4) //With printing

http://www.spoj.com/problems/ADABRANC/

https://www.spoj.com/problems/CONSEC/ (4) //[NICE][OFFLINE]

https://codeforces.com/gym/102006/problem/C (4) //[NICE][BRUTE-FORCE]

http://codeforces.com/gym/101962/problem/J (5) //[VERY NICE][TREE-FAT][SPARSE]

http://codeforces.com/contest/915/problem/F (6) //[VERY NICE][SORTING]

http://codeforces.com/contest/141/problem/E (6) //[NICE][SPANNIG TREE]

7903 — Pandaria (7) //[VERY NICE][DSU][SORTING][MERGE][DFS]

http://codeforces.com/contest/110/problem/E (4) //[NICE][COMBINATORICS][TREE]

http://codeforces.com/contest/90/problem/E (5) //[NICE][DSU-LIKE-LINKS][SIMULATION]

http://codeforces.com/contest/87/problem/D (5) //[VERY NICE][SORTING][COMPRES][DFS]

http://codeforces.com/contest/884/problem/E (5) //[VERY NICE][MEMORY SPARSE]

http://codeforces.com/contest/60/problem/D (6) //[NICE][Pythagorean Triples][Gen over max!]

UVA 10947

UVA 12363

LA 3833

http://codeforces.com/problemset/problem/742/D //+DP

UVA 10178

http://codeforces.com/contest/723/problem/F 7

13153 UVA (5)

13169 UVA (3)

11987 UVA (3)

11474 UVA (4)

http://www.spoj.com/problems/BTCODE_G/

http://codeforces.com/problemset/problem/691/D

Gym 101174K [2016-2017 ACM-ICPC Southwestern European Regional Programming Contest (SWERC 2016)]

UVA 10583

LightOJ 1003

http://codeforces.com/problemset/problem/731/C

UVA 793

UVA 11966

https://www.codechef.com/problems/COZIC

3939 [LA]

UVA 11503

http://codeforces.com/problemset/problem/755/C

UVA 1395

http://codeforces.com/contest/687/problem/D 6

http://codeforces.com/contest/680/problem/E 7 //+precalculation/brute force

http://codeforces.com/contest/766/problem/D 5

http://www.spoj.com/problems/LEXSTR/ (3) //Nice na stringu

http://codeforces.com/contest/805/problem/C 3 //NICE (dijkstra like :P)

http://www.spoj.com/problems/IITKWPCI/ (3) //VERY NICE

http://www.spoj.com/problems/FRNDCIRC (3) //Classical DSU (NICE for practice)

http://www.spoj.com/problems/FOXLINGS/ (3) Easy — just renumbering

http://www.spoj.com/problems/NITTROAD/ (4) //Process from back

http://www.spoj.com/problems/SHAHBG/ (2) //DSU not needes (simulated by array)

http://codeforces.com/contest/598/problem/D (3) //Can be solved with DFS too

http://codeforces.com/contest/9/problem/E (4) //Making one big cycle

http://codeforces.com/contest/25/problem/D (4) //Could be done linear too

http://codeforces.com/contest/28/problem/B (4) //NICE [imho bad statement]

http://codeforces.com/contest/876/problem/D (4) //DSU adjacent + visited

http://codeforces.com/contest/875/problem/F (6) //NICE — Maximum cactus-forest [kruskal-like]

http://codeforces.com/gym/101879/problem/C (6) //[VERY NICE][DFS]

http://codeforces.com/contest/907/problem/F (7) //[MAGIC]

UVA 10299

UVA 10990

https://www.codechef.com/problems/SMPLSUM

https://www.codechef.com/problems/COZIE

http://www.spoj.com/problems/LCMSUM/

Gym 100975F [2003-2004 Petrozavodsk Summer Training Camp, Saratov SU Contest]

UVA 13132

http://www.spoj.com/problems/GCDEX/

UVA 12995

http://www.spoj.com/problems/TIP1/

UVA 11327

LightOJ 1007

http://www.spoj.com/problems/ETF/

Project Euler #72: Counting fractions

http://www.spoj.com/problems/DCEPCA03/

http://www.spoj.com/problems/NAJPWG/ 4 //Gauss-Euler

http://www.spoj.com/problems/DCEPC12G/ (5) //Do what is written there

http://www.spoj.com/problems/INVPHI/ (5) //Inverse euler

https://codeforces.com/gym/102006/problem/H (4) //[SORTING][OBSERVATION]

http://codeforces.com/gym/101650 I //[NICE][GRAPHS]// Theory is useful

13246 — Chained Words (4) //[NICE][LEXICOGRAPHICAL]

UVA 10735

http://codeforces.com/contest/789/problem/D //Adj EG + Self/everything

http://codeforces.com/contest/21/problem/D (5) //[NICE][EulerTour+DP]

http://codeforces.com/contest/36/problem/E (6) //VERY NICE [4odd is hardest]

http://www.spoj.com/problems/ADAHW/ [RHO][Number Theory]

http://www.spoj.com/problems/ADADIGIT/ [Permutations]

https://www.spoj.com/problems/PRIMEP/ (5) //[VERY NICE][SEGMENT][BS][SIEVE]

https://codeforces.com/gym/101981 J //[NICE][DIVIDE]

http://codeforces.com/gym/101801 B

UVA 13067

Project Euler #108: Diophantine reciprocals I

http://www.spoj.com/problems/CHGROOM/

Gym 101370A [2009-2010 Summer Petrozavodsk Camp, Petr Mitrichev Contest 5]

http://codeforces.com/problemset/problem/837/E

http://www.spoj.com/problems/PSYCHOT/

http://www.spoj.com/problems/FACTDIV/

http://www.spoj.com/problems/NOSQ/

http://www.spoj.com/problems/FCDC/

http://www.spoj.com/problems/NFACTOR/

http://www.spoj.com/problems/ABA12D/

http://www.spoj.com/problems/PSTR/

http://www.spoj.com/problems/AMR11E/

http://www.spoj.com/problems/FACT1/

http://www.spoj.com/problems/FACT2/

https://www.hackerearth.com/problem/algorithm/gold-at-lolympics/

12005 UVA (7)

12062 UVA (6)

11960 UVA (3)

http://www.spoj.com/problems/FACTCG2/ (3)

http://www.spoj.com/problems/FACT0/ (4)

http://codeforces.com/contest/546/problem/D 5

http://codeforces.com/contest/222/problem/C 6

http://www.spoj.com/problems/COMDIV/ 3

http://www.spoj.com/problems/SINEGGS/ 3

http://www.spoj.com/problems/BDOI16B/ 4

http://www.spoj.com/problems/HG/ 4 //Map == OK

11099 UVA (3) //factor + recursion

13194 UVA (3) //factorize+generate /or just check

13191 UVA (6) //Pollard-Rho

http://codeforces.com/contest/818/problem/E (4) // Efficient + Two Pointers

http://codeforces.com/contest/831/problem/F (6) //MAGIC

http://codeforces.com/contest/839/problem/D (4) // Combinatorics + IE

http://www.spoj.com/problems/SAS002/ (5) //Find all divisors (big numbers)

http://www.spoj.com/problems/GCDS/ (4) //Lowest unused prime

http://www.spoj.com/problems/IITKWPCF/ (4) //Nonprime divisors of N/2

http://codeforces.com/contest/851/problem/D (4) //Properties of GCD + factor: NICE

http://www.spoj.com/problems/PTIME/ (3) //Low bounds — check each prime independently

http://www.spoj.com/problems/MAIN12B/ (3) //NICE [Factorization][Sort][Unique]

http://www.spoj.com/problems/AMR11E/ (2) //2664 is the biggest

http://www.spoj.com/problems/GCPC11A/ (4) //Very nice — factorize + divide N by powers

http://www.spoj.com/problems/AMR10C/ (3) //Maximum of factor-powers

http://www.spoj.com/problems/ADABEHIVE/ [2D]

http://www.spoj.com/problems/ADACABAA/ [2D][Sparse]

https://codeforces.com/contest/1191/problem/F (5) //[NICE][SORTING]Or similar DS

https://codeforces.com/gym/102001/problem/H (4) //[NICE][GREEDY]

https://toph.co/p/easy-prime (4) //[EASY][SIEVE]

https://toph.co/p/mario-and-princess-peach (5) //[NICE][DP][SEGMENT TREE][MAX]

http://codeforces.com/gym/101628/problem/B (5) //[NICE][SPARSE][STL]

http://codeforces.com/gym/100112 (4) [B] //[NICE][INVERSION][OBSERVATION]

http://codeforces.com/gym/101982 (7) [I] //[VERY NICE][INVERSION][OBSERVATION]

http://codeforces.com/gym/101908/problem/C (4) //[MATH][INVERSION]

http://codeforces.com/gym/101889 (5) //[NICE] normalize

DevSkills-422: Double Pairs (4) //[NICE] normalize

7591 — Distribution Center (4) //[NICE][SORTING]

http://codeforces.com/contest/903/problem/D (5) //[NICE][BIG]

http://codeforces.com/contest/102/problem/D (4) //[NICE][+DP][NORMALIZE]

http://codeforces.com/gym/101047/problem/J [2D]

http://www.spoj.com/problems/MATSUM/ [2D]

https://www.hackerearth.com/practice/data-structures/advanced-data-structures/fenwick-binary-indexed-trees/practice-problems/algorithm/counting-in-byteland/ [3D]

https://devskill.com/CodingProblems/ViewProblem/300

http://codeforces.com/contest/707/problem/E 7 [2D]

http://codeforces.com/contest/749/problem/E 8

http://codeforces.com/problemset/gymProblem/101055/D 5 [2D]

11240 UVA (4)

http://codeforces.com/contest/459/problem/D (4) //[NICE][SWEEPING]

http://codeforces.com/contest/61/problem/E (4) //[NICE][CLASSICAL][2*FW][NORMALIZE]

http://codeforces.com/contest/669/problem/E 5 //fenwicks — sparse

http://codeforces.com/contest/777/problem/E 4 //MAXIMUM

http://www.spoj.com/problems/TULIPNUM/ 4 //inc — 1 nor+num|sum(A[B],A[E])

http://codeforces.com/contest/799/problem/C 3 //MAX FW (but possibly easier?)

http://codeforces.com/contest/831/problem/E 4 //MAP to get ORDER — FW == LIST

http://www.spoj.com/problems/SAS001/ (4) //Nice — number of inversions + 2P

http://www.spoj.com/problems/TPGA/ (4) //NICE — Lesser*(N-i-1)!

http://www.spoj.com/problems/SGIFT/ (4) //BS works too

http://www.spoj.com/problems/SUMSUM/ (5) //Bit-by-Bit cnt 0/1

http://www.spoj.com/problems/AKVQLD03/ (3) //Classical fenwick — easy

http://www.spoj.com/problems/ZIGZAG2/ (6) //Very nice — FW + BS + DP

http://codeforces.com/contest/849/problem/E (7) //2D Fenwick / ST+TP [NICE]

http://www.spoj.com/problems/CRAYON/ (5) //VERY NICE [2*FW — begin + end]

http://www.spoj.com/problems/NITT8/ (4) //Norm. + Store indices in MAX-Fenwick [REVERSE] [VERY NICE]

http://www.spoj.com/problems/DCEPC705/ (4) //NICE! Sort + Fenwick

http://www.spoj.com/problems/DCEPC206/ (3) //NICE & EASY

http://www.spoj.com/problems/KOPC12G/ (4) //N Fenwick trees

http://www.spoj.com/problems/TRIPINV/ (4) //2xFenwick (triples counting)

http://codeforces.com/contest/597/problem/C (4) //[VERY NICE] 11*Fenwick

http://codeforces.com/contest/12/problem/D (4) //NICE [triplet-comparing][sort]

https://www.spoj.com/problems/NARHIL/ // Sugested by ak07_

http://www.spoj.com/problems/ADAMATCH/

https://toph.co/p/play-the-lottery (7) //[VERY NICE][D&C][MODULAR]

UVA 12633

6886 — Golf Bot [LA]

http://www.spoj.com/problems/POLYMUL/en/

Gym 100960C [2015-2016 Petrozavodsk Winter Training Camp, Nizhny Novgorod SU Contest]

https://www.codechef.com/problems/APRPS

https://www.codechef.com/problems/POLYEVAL

http://www.spoj.com/problems/TSUM/ 5

13182 UVA 5 //ACTG hamming

http://codeforces.com/contest/827/problem/E (8) //MAGIC

http://www.spoj.com/problems/MAXMATCH/ 5 //abc hamming

https://www.spoj.com/problems/DISGRAPH/ (5) //Stoer-Wagner [global]

https://codeforces.com/gym/101981 I //[NICE]

http://codeforces.com/gym/101982 E //[VERY NICE][GRID]

http://codeforces.com/gym/101845/problem/F (4) //Basic

http://codeforces.com/gym/101908/problem/G (4) //[NICE][MATCHING][BS]

http://www.spoj.com/problems/FASTFLOW/en/ //Raw (no sauce)

http://codeforces.com/contest/78/problem/E (5) //NICE [Matching-like][+BFS]

4322 — Destroying the bus stations (Live Archive)

11380 — Down Went The Titanic (UVA) //Interesting grid problem

6395 — Surely You Congest (LA) //VERY NICE [slightly advanced]

7204 — Blood groups (LA)

http://codeforces.com/gym/100963 (Flame of Nucleus — F)

11167 — Monkeys in the Emei Mountain //Also harder (imho)

http://codeforces.com/problemset/problem/653/D (+BS)

13000 — VIP Treatment (+BS)

1242 — Necklace

https://www.deadline24.pl/assets/problemsets/dl24.elim.2017.B.en.pdf (DEADLINE 24 problem — not sure if it can be submited :O)

3487 — Duopoly (Near matching)

http://codeforces.com/problemset/problem/727/D

http://codeforces.com/problemset/problem/704/D [Also advanced]

5418 — A Plug for UNIX (LA)

4957 — Fake scoreboard (LA) //If I remember well, other solutions was also possible

1155 — Power Transmission (LOJ) //(classical)

https://www.codechef.com/problems/ROBOTDAG //Ford-Fukherson

10804 — Gopher Strategy (UVA)

11506 — Angry Programmer (UVA) //Nodes division

10511 — Councilling (UVA)

563 — Crimewave

1306 — The K-League (UVA)

1345 — Jamie's Contact Groups

10092 — The Problem with the Problem Setter

Problem B. Roller Coaster Scheduling (GCJ — 2017)

259 — Software Allocation (UVA)

5905 — Pool construction (LA) //Imho harder

10480 — Sabotage

http://codeforces.com/contest/808/problem/F 6 //NICE — nontrivial (max matching with bigger flows)

http://codeforces.com/contest/847/problem/J 6 //Probably not flows — matching-like

http://www.spoj.com/problems/ADAHOSE/ [DUAL-GRAPH]

http://codeforces.com/contest/903/problem/G (6) //[VERY NICE][SEG-TREE][CUT]

3837 [LA] //Stable Marriage

UVA 1175 //Stable Marriage

11594 — All Pairs Maximum Flow (UVA)

http://www.spoj.com/problems/ADABLOOM/ //Maximum matching in general graph

11439 — Maximizing the ICPC //Maximum matching in general graph

1376 — Animal Run //Max flow on planar graph (Dual == shortest path over edges)

10989 — Bomb, Divide and Conquer //Stoer-Wagner — global cut

https://codeforces.com/contest/1202/problem/B (3) //[VERY NICE]

http://codeforces.com/gym/101845/problem/C

https://www.urionlinejudge.com.br/judge/en/problems/view/2676 (3) //simple FW

10724 UVA

UVA 117

http://codeforces.com/problemset/problem/21/D

UVA 1198

LightOJ 1086 //+DP

http://www.spoj.com/problems/INGRED/ //+DP

UVA 10048

UVA 125

Gym 101223C [2017 Facebook Hacker Cup, Round 1] //+DP

LightOJ 1221

UVA 423

UVA 12179 //+DP

UVA 1416

UVA 1233

UVA 10793

10099 UVA

UVA 869

LightOJ 1174

http://www.spoj.com/problems/ARBITRAG/ //Other algos shall work too

13211 UVA (5) //NICE — FW adding states

http://www.spoj.com/problems/ROHAAN/ (3) //Classical

http://codeforces.com/contest/25/problem/C (4) //Adding new edges .. need FW principal

http://codeforces.com/contest/33/problem/B (3) //NICE [dijkstra could work too]

http://www.spoj.com/problems/ADAPOWER/

4956 [LA]

http://www.spoj.com/problems/ADAGAME/ [DP]

http://www.spoj.com/problems/ADAGAME2/

http://www.spoj.com/problems/ADAGAME4/

http://www.spoj.com/problems/ADAQUBIC/

http://www.spoj.com/problems/ADAFIMBR/

http://www.spoj.com/problems/ADAGAME5/

http://www.spoj.com/problems/ADAXMAS/

https://codeforces.com/contest/1194/problem/D (4) //[OBSERVATIO][PATTERN]

https://codeforces.com/contest/1191/problem/E (4) //[NICE][IF][OBSERVATION]

https://www.spoj.com/problems/HUSGAME/ (4) //[VERY NICE][OBSERVATION][RECURSION]

https://www.spoj.com/problems/IBIGAME/ (5) //[VERY NICE][OBSERVATION][DP]

https://codeforces.com/gym/101981 A

https://codeforces.com/gym/102058/problem/F (4) //[NICE]

http://codeforces.com/gym/101801 F //[EASY][OBSERVATION][NIM]

http://codeforces.com/gym/101908/problem/B (5) //[NICE][NIMBERS][OBSERVATION]

http://codeforces.com/gym/101873 H //[VERY NICE][OBSERVATION][TREE] //LUP LUP

http://codeforces.com/gym/101808/problem/I (5) //[DP][OBSERVATION]

http://codeforces.com/contest/919/problem/F (6) //[NICE][HARD][IMPLE][BFS][TOPO][GRAF]

http://codeforces.com/contest/918/problem/D (4) //[NICE][DAG][DP][TREE]

http://codeforces.com/contest/914/problem/B (3) //[NICE][EASY][OBSERVATION][PARITY]

http://codeforces.com/contest/148/problem/D (4) //[EASY][DP][PROBABILITY]

http://codeforces.com/contest/138/problem/D (7) //[VERY NICE][DP][OBSERVATION]

https://arc087.contest.atcoder.jp/tasks/arc087_c (5) //[VERY NICE][TRIE][SEQUENCE]

http://codeforces.com/contest/120/problem/E (3) //[NICE][SYMETRY][PARITY]

http://codeforces.com/contest/88/problem/E (5) //[VERY NICE][PREFIX-XOR][NIMBERS][SQRT][MATH]

http://codeforces.com/contest/69/problem/D (4) //[NICE][DP] Reflection can be ignored

http://codeforces.com/contest/55/problem/C (4) //[NICE] Size of piece from border

http://codeforces.com/problemset/problem/255/E --MEX

https://devskill.com/CodingProblems/ViewProblem/91

https://devskill.com/CodingProblems/ViewProblem/364

Project Euler #96: Su Doku //Sudoku

11859 UVA 4

11863 UVA 4

11892 UVA 3 //Probably solved by many

11534 UVA 5

http://www.spoj.com/problems/VECTAR11/ 4 //Nsqrt(N) passes [with break]

http://codeforces.com/contest/768/problem/E (4) //NICE — Grundy

http://www.spoj.com/problems/SYNC13C/ (4) //2*DP {maybe not seeing sth}

http://codeforces.com/contest/787/problem/C (4)

http://codeforces.com/contest/794/problem/C (3) //Find optimal strategy: choose back/front

http://codeforces.com/contest/794/problem/E (5) //NICE Find stategy: Even/Odd

http://codeforces.com/contest/812/problem/E (7) //Advanced NIM strategy

http://www.spoj.com/problems/GAMEMVS/ (4) //Nimbers (Ai^X)<=Ai

http://www.spoj.com/problems/PLAYGAME/ (3) //Check pattern

http://www.spoj.com/problems/CHAOS_CC/ (4) //VERY NICE [nimbers]

http://codeforces.com/contest/851/problem/E (5) //Very nice [nimbers] [bitset]

http://www.spoj.com/problems/CHGROOM/ (4) //+Factorisation [NICE & Easy]: Win unless 2 prime factors

http://www.spoj.com/problems/EALP1/ (4) //NICE ~ Possible Moves of NIM

http://www.spoj.com/problems/GAME3/ (4) //VERY NICE — pattern watching [A145812]

http://www.spoj.com/problems/GAME2/ (5) //VERY NICE — https://community.topcoder.com/tc?module=Static&d1=match_editorials&d2=srm338 (CAKE)

http://www.spoj.com/problems/CF36D/ (5) //Pattern watching (care for 1)

http://codeforces.com/contest/15/problem/C (4) //VERY NICE [XOR: A,1,A+1,0..repeat]

http://codeforces.com/contest/39/problem/E (4) //Slightly [DP][MATH][ROUNDING]

http://codeforces.com/contest/63/problem/E (5) //[NICE][BITMASK-DP]

12910 — Snakes and Ladders [UVA]

UVA 10828

http://codeforces.com/gym/100923/problem/C

4963 [LA]

UVA 12849

Gym 100962A [2015-2016 Petrozavodsk Winter Training Camp, Moscow SU Trinity Contest][NICE]

UVA 10109 [NICE][HARD-WORK]

http://www.spoj.com/problems/ADAPICK/

http://www.spoj.com/problems/ADAKOHL/

https://codeforces.com/contest/1199/problem/B (2) //[NICE][SIMPLE]

https://codeforces.com/gym/101991/problem/J (5)

https://codeforces.com/gym/101991/problem/B (4)

https://codeforces.com/gym/102006/problem/I (4) //[VERY NICE][ITERATIVE]

https://codeforces.com/gym/102021 G //[3D]

https://codeforces.com/gym/102021 B //Path on circle

https://codeforces.com/gym/102058/problem/K (3) //[BRUTE-FORCE][FAIL]

https://codeforces.com/gym/101972/problem/C (4) //[EASY][POINTS DISTANCE][IMAGE]

http://codeforces.com/gym/101628/problem/C (4) //Circles intersection

http://codeforces.com/gym/100112 G //Special cases and so on — imple.

http://codeforces.com/gym/101982 G //[DISTANCE]

http://codeforces.com/gym/101845/problem/D (5) //[VERY NICE][POLYGON][MO]

http://codeforces.com/gym/101962/problem/G (5) //Angles

http://codeforces.com/gym/101908/problem/K

http://codeforces.com/gym/101879/problem/A (7)

http://codeforces.com/gym/101873 G //Pick's Theorem

http://codeforces.com/gym/101873 A //heavy implementation

http://codeforces.com/gym/101808/problem/E (5)

http://codeforces.com/gym/101808/problem/A (2)

http://codeforces.com/gym/101666 A

http://codeforces.com/gym/101726/problem/J (5) //[NICE][INTERSECTION][DS]

http://codeforces.com/gym/101650 F //Polygons + circles

http://codeforces.com/gym/101650 H //A few if's

http://codeforces.com/contest/908/problem/C (3)

http://codeforces.com/contest/140/problem/A (3) //Circles around bigger circle

http://codeforces.com/contest/136/problem/D (4) //+Brute-Force

http://codeforces.com/contest/127/problem/A (1) //Points distance

http://codeforces.com/gym/101597/problem/B (3) //Simply brute-force just the closest to points

http://codeforces.com/contest/70/problem/D (5) //Dynamic Convex Hull

https://icpc.kattis.com/problems/airport //Proposed by Tutis

https://www.hackerrank.com/contests/world-codesprint-7/challenges/elastic-rope/problem

https://devskill.com/CodingProblems/ViewProblem/20 [EASY]

UVA 10321 //Polygon intersection

UVA 11265 //Polygon point +/-

UVA 13112 //Polygon

10907 UVA [Area of polygon from a point]

3378 — Swamp Things [LA] — Maximum points on line

UVA 11768 //Discrete points

2542 [LA] //Arc size [formula]

UVA 1571 //As below [easier]

https://www.codechef.com/problems/ALLPOLY //[NICE] Point seeing polygon

http://www.spoj.com/problems/IITKWPCL/ //Point distance

UVA 11281 //circle~triangle

UVA 12921 //circle reconstruction

UVA 190 //circle from 3 points

UVA 12240 //pts>circle

UVA 438 //circle pt

LightOJ 1018 //Minimum # of lines through all pts [VERY NICE]

UVA 11008 //Similar as above

UVA 12830 //Biggest rectangle without points inside

UVA 11012 //Most distant points

UVA 1683 //Closest points

UVA 12389 //3D MH Closest Points

http://www.spoj.com/problems/AMR12C/ //Pt closest to all other points

http://www.spoj.com/problems/CLOPPAIR/ //Closest pair of points

UVA 10678 //Circles intersection

http://codeforces.com/problemset/problem/600/D //Circles intersection

LightOJ 1118 //Circles intersection

http://www.spoj.com/problems/CERC07C/en/ //Bounding circle

UVA-10005 //Bounding circle

2407 [LA] //Bounding Sphere

LightOJ 1120 //Rectangle's Union

LightOJ 1130 //Circle x Rectangle intersection

UVA 11177 //Circle x Convex Polygon

http://codeforces.com/problemset/problem/610/D //Lines intersections (axes parallel)

6263 [LA] //Pt in areas

LightOJ 1058 //# parallelograma

UVA 12931 //Common area of polygons

UVA 10301 //Intersecting circles

UVA 453 //Circles intersection

http://codeforces.com/problemset/problem/681/E //Circles intersection

UVA 920 //Lines intersecion (etc..)

UVA 12556

http://codeforces.com/problemset/problem/793/C //Intersection ans similar

UVA 11343 //Intersection of segments

UVA 866 //Intersection of segments

Gym 100190I [2011 ACM-ICPC East Central North America (ECNA 2011)] //Segment intersection

http://codeforces.com/gym/100917/problem/K

UVA 11686 //Segment intersection

LightOJ 1388

UVA 833 //Segment intersection

LightOJ 1196 //Points sides

UVA 10167 //Points sides

UVA 12818 //Arc & Point distance

http://www.spoj.com/problems/SICRANO/ //Point-line distance

http://codeforces.com/problemset/problem/614/C //Point-line distance

UVA 13117 //Point-line distance

UVA 12483 //Point-line distance

UVA 12173 //Point-line distance

UVA 10075 //Point distance on sphere

https://www.hackerrank.com/contests/booking-hackathon/challenges/nearby-attractions/problem //Pt sphr

UVA 535 //Point distance on sphere

UVA 10897 //Sphere tavelling

UVA 11817 //Sphere travelling

UVA 10316 //Sphere travelling

UVA 1469 //Fractions distance 3D

11930

12173 UVA 3

12194 UVA 4

11894 UVA 3

11769 UVA 7

11665 UVA 5

11509 UVA 4

11355 UVA 5

11265 UVA 6 //Nice one | polygon — cut/pt-check/area

11123 UVA 4 //Counting trapezoids

11177 UVA 6 //BS+Polygon/Circle intersection

11186 UVA 3

11008 UVA 5 //with DP → #intersected triangles

11012 UVA 5 //Nejvzdálenější body (Manhatton 3D)

11072 UVA 4 //Points v poly gonu

http://codeforces.com/problemset/problem/682/E 6 (biggest triangle)

http://codeforces.com/contest/672/problem/C 4 //easy — just think it up

http://codeforces.com/contest/667/problem/A 2 //vzorecky

http://codeforces.com/contest/793/problem/C 5 //EASY but beware of epsilons (NICE)

http://codeforces.com/contest/794/problem/B 2 //Can be done with BS

http://codeforces.com/contest/814/problem/D 5 //+DP on trees (NICE — but low geom.)

10750 UVA 3 //Closest points — try all pairs

http://codeforces.com/contest/820/problem/B 3 //Polygon angle find!

13213 UVA 5 //VERY NICE — Voronoi diagram (low constraints so not actually needed)

13215 UVA 3 //EASY — Sum areas and find side lengths

http://www.spoj.com/problems/IITKWPCC/ (5) //VERY VERY NICE — Nqrt(N)log(N)

http://www.spoj.com/problems/NNS/ (5) Closest points query [fake geometry] {__128}[NICE]

http://codeforces.com/contest/849/problem/B (3) //X-Product — side

http://www.spoj.com/problems/AMR12C/ (5) //Point closest to all other points (with speed)

http://www.spoj.com/problems/SICRANO/ (3) //Line-Point distance

http://www.spoj.com/problems/VCIRCLES/ (5) //Heavy geometrical ****

http://www.spoj.com/problems/CIRU/ (5) //Same as above [yet bigger constraints]

http://www.spoj.com/problems/THREETW1/ (4) //Fermat point search

http://www.spoj.com/problems/CLOPPAIR/ (4) //Closest pair of points

http://www.spoj.com/problems/MAXLN/ (2) //Some basic (4*r^2+.25)

http://www.spoj.com/problems/KOLICA/ (4) //VERY NICE [nasty iff party]

http://codeforces.com/contest/598/problem/C (4) //NICE ~ Precision! [ld]

http://codeforces.com/contest/18/problem/A (2) //EASY&FINE: Pythagoreas

http://codeforces.com/contest/40/problem/A (2) //[EASY][DISTANCE]

https://codeforces.com/contest/1182/problem/D (5) //[CENTRUM][OBSERVATION][DFS]

https://www.urionlinejudge.com.br/judge/en/problems/view/1562 (5) //[VERY NICE][QUEUE][GREEDY]

https://codeforces.com/gym/102001/problem/G (4) //[NICE][BS]

https://codeforces.com/gym/102006/problem/G (4) //[NICE][TOPOSORT][OBSERVATION]

https://codeforces.com/gym/102058/problem/B (6) //[VERY NICE][REVERSE-SIMULATION]

http://codeforces.com/gym/101666 H //[VERY NICE][GEOMETRY][DSU][EULER][PLANAR]

2827 [LA] //3Coloring

2243 [LA] //3Coloring

5603 [LA] //Coloring

UVA 1658 //Shortest paths

UVA 12821 //Shortest paths

http://codeforces.com/contest/27/problem/D (5)

11387 (UVA) 4

http://www.spoj.com/problems/VFRIEND2/ (5) //Graph possible check

http://codeforces.com/contest/859/problem/E (4) //VERY NICE (2 cases: CYCLE [x2] / TREE [x(Size+1)]

http://codeforces.com/contest/847/problem/C (2) //Forest making Easy&Nice

http://codeforces.com/contest/863/problem/C (3) //Cycle in states

https://codeforces.com/contest/1175/problem/D (4) //[NICE][PREPROCESS][SORTING]

https://codeforces.com/contest/1203/problem/F1 (5) //[VERY NICE][SORTING][CASES]

https://codeforces.com/contest/1176/problem/C (3) //[SIMPLE][NICE][IMPLE]

https://codeforces.com/contest/1176/problem/A (1)

https://codeforces.com/contest/1200/problem/B (3) //[SIMPLE][NICE]

https://codeforces.com/contest/1202/problem/A (2)

https://codeforces.com/contest/1181/problem/B (4) //[BIG]

https://atcoder.jp/contests/abc136/tasks/abc136_c (3) //[REVERSE]

https://codeforces.com/contest/1185/problem/C2 (4)

https://codeforces.com/contest/1185/problem/B (2) //[EASY]

https://codeforces.com/contest/1180/problem/B (3) //[IMPLEMENTATION][MATH]

https://codeforces.com/contest/1186/problem/D (4) //[IMPLEMENTATION]

https://codeforces.com/contest/1197/problem/B (3) //[BITONIC][IMPLE]

https://www.spoj.com/problems/DIVSTR/ (3) //[CUTE]

https://codeforces.com/gym/101981 E //[NICE][NORMALIZE][STACK]

https://codeforces.com/gym/102001/problem/L (3) //[BITS]

https://toph.co/p/passwords (2)

http://codeforces.com/gym/100112 (3) //[FINE]

http://codeforces.com/gym/101666 (4) //[NICE][QUEUE][DFS][EVENTS]

http://codeforces.com/gym/101806/problem/T (5) //[NICE][SEGMENT TREE][SORTING]

http://codeforces.com/contest/916/problem/B (3) //[BITS] FIRST & LAST

http://codeforces.com/contest/913/problem/C (3) //+[DP]

http://codeforces.com/contest/146/problem/D (4) //[NICE][CONSTRUCTION]

http://codeforces.com/contest/146/problem/C (3) //[EASY][NICE][TWO-CASES]

http://codeforces.com/contest/139/problem/D (4) //Muchas cases

7887 — Back to the Future (4) //[NICE][2*HEAP]

http://codeforces.com/contest/910/problem/A (2) //DP works too

http://codeforces.com/contest/125/problem/D (4) //Limited possibilities

http://codeforces.com/contest/902/problem/A (2) //Just keep last

http://codeforces.com/contest/898/problem/D (4) //[NICE][FENWICK/OR/PREFIX]

http://codeforces.com/contest/118/problem/C (4) //[NICE] — Try each digit (iterate in waves)

7706 — Pokemons (2) //Sweep and keep maximum

http://codeforces.com/contest/893/problem/D (4) //[NICE][SWEEP][MAXIMUM] — pay max when have to

http://codeforces.com/contest/892/problem/B (2) //Sweep from back

http://codeforces.com/contest/102/problem/C (3) //sort by frequency

https://devskill.com/CodingProblems/ViewProblem/419 (2) //Sweep from back

http://codeforces.com/contest/890/problem/C (3) //frequence

http://codeforces.com/contest/890/problem/B (2) //[EASY][REVERSE]

http://codeforces.com/contest/888/problem/B (2) //Equalize U/D and L/R

http://codeforces.com/gym/101597/problem/J (4) //[NICE][SWEEP]

http://codeforces.com/contest/76/problem/B (4) //[NICE][MATCHING-LIKE][2PTRS]

http://codeforces.com/contest/73/problem/B (4) //[IMPLEMENTATION][SORTING]

http://codeforces.com/contest/883/problem/K (4) //Nice — Two sweeps

http://codeforces.com/contest/49/problem/D (3) //NICE — 1010101 OR 0101010 [haming]

http://codeforces.com/contest/58/problem/C (4) //NICE — group trees by slopes

http://codeforces.com/contest/729/problem/D 3

http://codeforces.com/contest/729/problem/E 4

http://codeforces.com/contest/725/problem/D 4

http://codeforces.com/contest/725/problem/F 9

http://codeforces.com/contest/732/problem/E 5

http://codeforces.com/contest/727/problem/F 6

http://codeforces.com/contest/724/problem/D 5

http://codeforces.com/contest/723/problem/C 4

http://codeforces.com/contest/719/problem/B 2

http://codeforces.com/contest/712/problem/C 3

13152 UVA (4)

http://codeforces.com/contest/746/problem/E 5

http://codeforces.com/contest/746/problem/D 3

http://codeforces.com/contest/749/problem/C 3

11737 UVA (3)

11786 UVA (4)

11630 UVA (5)

11563 UVA (4)

11491 UVA (4)

11330 UVA (3)

11089 UVA (2)

http://codeforces.com/contest/884/problem/D (4) //PQ or Sort

http://www.spoj.com/problems/SQRMINSUM/ 3 //solve-able in O(N+M)-arrayqueue

http://www.spoj.com/problems/MSCHED/ 3 //sweep from back

http://www.spoj.com/status/ns=18780683 4 //all perm + A<B<C works

http://www.spoj.com/problems/NINJA7/ (3) //sort by diff

http://www.spoj.com/problems/NINJA2/ (4) //try all possib. (26)

http://codeforces.com/contest/767/problem/E (6)

http://codeforces.com/contest/637/problem/B (3) //NICE pro prvaky

http://codeforces.com/contest/777/problem/B (3) // -||-

http://codeforces.com/contest/777/problem/D (3) //just go from end

http://codeforces.com/contest/779/problem/C (3) //NICE pro prváky

http://www.spoj.com/problems/SPCU/ (2) //Easy — zamysleni (max int = index)

http://www.spoj.com/problems/LOPOV/ (4) //sort + queue (or just queue) NICE

http://codeforces.com/contest/792/problem/E (5) //T%S<=T/S + check proper

http://codeforces.com/contest/807/problem/E (5) //NICE — put asice P2 / rest — greedy from small

http://codeforces.com/contest/799/problem/E (5) //Many queues — but NICE

http://codeforces.com/contest/808/problem/C (3) //EASY

http://codeforces.com/contest/802/problem/B (4) //Priority by "next"

10850 UVA (4) //Queue a brute-force

http://codeforces.com/contest/813/problem/A (1) //Zahrivacka pro prvaky

10716 UVA (4) //NICE — always find closest pair

http://codeforces.com/contest/816/problem/C (3) //NICE — greater<lesser side

http://codeforces.com/contest/820/problem/D (5) //VERY NICE — O(N) -~- 5 events per number

http://codeforces.com/contest/818/problem/B (2) //Zahrivacka pro prvaky

http://codeforces.com/contest/822/problem/C (4) //Almost classical Sort+Queue

http://codeforces.com/contest/825/problem/C (2) //Nice & Easy

http://codeforces.com/contest/825/problem/D (3) //Update by modulo

http://codeforces.com/contest/835/problem/B (2) // Zahhrivacka pro prvaky

http://codeforces.com/contest/839/problem/B (3) //Nasty iffs — yet nice excersize

http://www.spoj.com/problems/PCPC12I/ (4) //Swipe MINIMUM from left/right [10^6-A[i] trick]

http://www.spoj.com/problems/AMR12I/ (3) //NICE a) MAX_SEG>=K b) (SEG_SIZE-1)/K+1

http://www.spoj.com/problems/BUSYMAN/ (2) //NICE&EASY — Sort + keep minimum

http://codeforces.com/contest/861/problem/C (3) //2+ but not same

http://www.spoj.com/problems/WORKB/ (3) //Simple "min" formula for each neighbor

http://codeforces.com/contest/864/problem/D (4) //VERY NICE — Frequency + unused

http://www.spoj.com/problems/ROADTRIP/ (4) //VERY NICE — Keeping last lesser

http://codeforces.com/contest/597/problem/B (3) //NICE [Classical]

http://www.spoj.com/problems/SHLIGHTS/ (4)

http://www.spoj.com/problems/MLK/ (3) //VERY NICE — Sum all prefix sums

http://codeforces.com/contest/867/problem/C (4) //NICE [IMPLE][2POINTERS][MID+EPS]

http://codeforces.com/contest/867/problem/E (5) //NICE [EASY-IMPLE][HARD-CONS]

http://codeforces.com/contest/18/problem/D (4) //+Big Integer

http://codeforces.com/contest/276/problem/D (4) //NICE — Find first mismatch bit (then 111...111)

http://codeforces.com/contest/3/problem/B (4) //Divide 1/2 [sort][2pointers]

http://codeforces.com/contest/3/problem/D (4) //?==) ..if open < 0: set max A-B to (

http://codeforces.com/contest/26/problem/B (4) // +1 ( | -1 ): -1, erase .. erase sum in the end

http://codeforces.com/contest/33/problem/A (2) //EASY [long-statement]

http://codeforces.com/contest/44/problem/E (2) //Try mins then try maxs

http://codeforces.com/contest/45/problem/D (3) //Priority-queue+'sort'

http://www.spoj.com/problems/ADACLEAN/

https://codeforces.com/contest/1200/problem/E (5) //[VERY NICE]

http://codeforces.com/gym/101808/problem/B (5) //[NICE][NUMBERS]

http://codeforces.com/gym/101741/problem/K (5) //[NICE][SQRT][PATTERN MATCHING]

7979 — Red Rover (3) //[NICE] //Many other ways to solve

http://codeforces.com/contest/898/problem/F (5) //[VERY NICE]//Hash by 10

http://codeforces.com/contest/114/problem/D (4) //[NICE] //N^2Log(N) might/might-not be OK

https://www.urionlinejudge.com.br/judge/en/problems/view/1503 (7) //[NICE][BS][OPTI]

Gym 101466E [2017 ACM-ICPC, Universidad Nacional de Colombia Programming Contest][NICE]

12012 UVA 4

http://codeforces.com/contest/727/problem/E 7

http://codeforces.com/contest/718/problem/D 8

11855 UVA 4

http://codeforces.com/contest/752/problem/D 5

http://codeforces.com/contest/825/problem/F 5 //String + Periods

http://codeforces.com/contest/835/problem/D 4 //Palindromes

http://www.spoj.com/problems/CF25E/ (5) //VERY NICE [IMPLE>CONCEPT]

http://codeforces.com/contest/7/problem/D (4) //Palindromes

http://codeforces.com/contest/19/problem/C (4) //[NICE]: Not a string

13300 — Ghost Hunting (4) //Hull + calipers passes

http://codeforces.com/gym/101982 M //[VERY NICE][HULL][TERNARY]

http://www.spoj.com/problems/GARDENHU/en/

2453 — Wall [LA]

UVA 13213

UVA 11096

Gym 100792G [2015-2016 ACM-ICPC, NEERC, Moscow Subregional Contest]

https://www.codechef.com/problems/KTHCON

http://codeforces.com/problemset/problem/605/C

UVA 218

UVA 11072

11168 UVA

UVA 12307

Gym 100963I [2007-2008 Summer Petrozavodsk Camp, Japanese Contest, 2007-08-29]

UVA 11243

UVA 10256

109 SCUD Busters

UVA 13024 [NICE]

UVA 10002

Gym 100886H [2015-2016 Petrozavodsk Winter Training Camp, Saratov SU Contest]

UVA 1139

UVA 681

UVA 811

https://www.codechef.com/problems/MGCHGEOM

UVA 11769 //3D

http://www.spoj.com/problems/ADACHESS/

http://www.spoj.com/problems/ADACHES2/

http://www.spoj.com/problems/ADAGAME5/

http://www.spoj.com/problems/ADAXMAS/

URI 1100 (3) //[BFS][KNIGHT]

https://www.codechef.com/problems/CHQUEENS (4) //[IMPLEMENTATION]

http://codeforces.com/contest/131/problem/E (4) //[NICE][STL][SORTING][QUEEN]

http://codeforces.com/contest/42/problem/B (4) //NICE — Checkmate check

UVA 10748 //bfs

LightOJ 1143

https://www.hackerearth.com/practice/algorithms/greedy/basics-of-greedy-algorithms/practice-problems/algorithm/harry-and-ron-play-a-game-of-chess/

UVA 10196

http://www.spoj.com/problems/KNMOVE/

UVA 11352

http://www.spoj.com/problems/NAKANJ/ //BFS

LightOJ 1010

LightOJ 1171 //MM

2883 LA

UVA 439

http://www.spoj.com/problems/TRKNIGHT/ //??

2308 LA

http://www.spoj.com/problems/CCHESS/ //Dijkstra

http://codeforces.com/problemset/problem/630/H //[ROOKS][BIG][COMBINATORICS]

LightOJ 1005 //As above (but with real rooks)

LightOJ 1061 //Placing queens

UVA 11085

UVA 10094 //Queen placing [NICE][PATTERN]

https://devskill.com/CodingProblems/ViewProblem/383

11852 UVA (6)

http://www.spoj.com/problems/KLUG1/ (2) //Jumps of horse

http://www.spoj.com/problems/CODESPTD/ (5) //VERY NICE — DP [Queens]

http://codeforces.com/contest/3/problem/A (2) //Imple — Shortest path for king

http://codeforces.com/contest/38/problem/B (2) //NICE — Simple possition checking

https://codeforces.com/contest/1203/problem/A (1) //[FOR][IF]

https://codeforces.com/contest/1173/problem/A (1) //[IF]

https://devskill.com/CodingProblems/ViewProblem/584 (2)

https://codeforces.com/contest/1200/problem/A (2) //[EASY]

https://codeforces.com/contest/1182/problem/B (3) //[PRACTICE][GRID-MOVEMENT]

https://codeforces.com/contest/1201/problem/B (2)

https://codeforces.com/contest/1201/problem/A (2)

https://atcoder.jp/contests/abc136/tasks/abc136_a (1)

https://codeforces.com/contest/1199/problem/A (2) //[BF]

https://codeforces.com/contest/1183/problem/A (2)

https://codeforces.com/contest/1186/problem/A (1)

https://codeforces.com/contest/1178/problem/A (2)

https://codeforces.com/contest/1195/problem/A (2) //[ARRAY]

https://codeforces.com/contest/1191/problem/A

https://www.spoj.com/problems/MOZHSLM/ (3) //Two sweeps

https://www.spoj.com/problems/OVGDEL/ (3) //[NICE][EASY][FREQUENCY]

https://www.spoj.com/problems/VTV1001/ (2)

https://codeforces.com/gym/102001/problem/D (3)

https://codeforces.com/gym/102021 (7) //[VERY NICE]Easy thought but nice imple

https://codeforces.com/gym/101972/problem/E (2)

https://codeforces.com/gym/101972/problem/D (1) //[IF]

https://toph.co/p/full-pyramid (1)

http://codeforces.com/gym/101992/problem/F (2)

http://codeforces.com/gym/101628/problem/D (3)

http://codeforces.com/gym/100112 I //[NICE][STRINGS][BITMASKS]

http://codeforces.com/gym/100112 A

http://codeforces.com/gym/101982 L

http://codeforces.com/gym/101982 J

http://codeforces.com/gym/101982 A //Easy

http://codeforces.com/gym/101845/problem/H (2) //Dates

http://codeforces.com/gym/101801 L

http://codeforces.com/gym/101801 A

http://codeforces.com/gym/101864 C //Easy

http://codeforces.com/gym/101889/my H

http://codeforces.com/contest/934/problem/A (2)

http://codeforces.com/contest/922/problem/A (2) //Iff-party

http://codeforces.com/contest/914/problem/A (1)

http://codeforces.com/contest/916/problem/A (2) //Time

http://codeforces.com/contest/915/problem/B (2) //Formula / Iff

http://codeforces.com/contest/915/problem/A (1)

http://codeforces.com/contest/913/problem/A (1)

http://codeforces.com/contest/912/problem/A (2) //Easy [corner-cases]

http://codeforces.com/contest/146/problem/A (1)

http://www.spoj.com/problems/ESYR/ (1) //Bad one :/

http://codeforces.com/contest/908/problem/A (1)

http://codeforces.com/contest/147/problem/A (2) //Parsing

http://codeforces.com/contest/139/problem/A (1)

http://codeforces.com/contest/137/problem/A (1)

7886 — Assigning Teams (2) //[EASY][SORTING]

http://codeforces.com/contest/133/problem/A (1)

http://codeforces.com/contest/134/problem/A (1)

http://codeforces.com/contest/131/problem/A (1)

http://codeforces.com/contest/127/problem/B (1) [EASY]

http://codeforces.com/contest/899/problem/B (2) //Dates

http://codeforces.com/contest/898/problem/C (3) //No thinking — just implementation

6157 How do spiders walk on water? (4) //boring problem

http://codeforces.com/contest/900/problem/A (1)

7613 Relative atomic mass (1)

http://codeforces.com/contest/122/problem/A (1) //Find all lucky

http://codeforces.com/contest/120/problem/B (1) //Iteration

http://codeforces.com/contest/120/problem/A (1) //Iff/Logic

http://codeforces.com/contest/118/problem/B (2) //[PRINTING]

http://codeforces.com/contest/108/problem/A (1) //[EASY][PRINT][TIME]

http://codeforces.com/contest/106/problem/A (1) //Iff-party

http://codeforces.com/contest/890/problem/A (1) //if or perm

http://codeforces.com/contest/90/problem/B (2) //No idea — just cycles

http://codeforces.com/contest/75/problem/A (1) //conversion

http://codeforces.com/contest/884/problem/B (1) //Simple sum +N-1

http://codeforces.com/contest/48/problem/A (1) //Very easy [fe. perm]

http://codeforces.com/contest/51/my (2) //Lex-lowest-string (|s|=4)

http://codeforces.com/contest/54/problem/A (2) //Single sweep

http://codeforces.com/contest/719/problem/C 3

http://codeforces.com/contest/747/problem/E 4

http://codeforces.com/contest/754/problem/C 5

11482 UVA (4)

11291 UVA (3)

11070 UVA (5) //evaluation of expression

11074 UVA (2)

http://codeforces.com/contest/678/problem/B 2 //calendar days

http://codeforces.com/contest/643/problem/A 3 //easy — just simulate

http://codeforces.com/contest/770/problem/D 5 //easy — but pain — draw

http://codeforces.com/contest/789/problem/B 3 //simulate (mby twice)

13171 UVA (1)

10800 UVA (3)

http://codeforces.com/contest/828/problem/B 2 //EASY & NICE — just analysis

http://codeforces.com/contest/825/problem/B 2 //EASY & NICE — Piskvorky — pro prvaky

http://codeforces.com/contest/837/problem/B 2 //Just implementation

http://codeforces.com/contest/837/problem/C 2 //Some nasty iffs

http://codeforces.com/contest/845/problem/B 2 //Easy pro prvaky

http://codeforces.com/contest/845/problem/D 3 //Iffs — folow the rules

http://www.spoj.com/problems/UNIHW/ 4 //NICE (but many iffs)

http://codeforces.com/contest/5/problem/A (2) //Parsing

http://codeforces.com/contest/5/problem/B (3) //Output formating

http://codeforces.com/contest/6/problem/B (2) //Simply check by adjancecy vector + set

http://codeforces.com/contest/7/problem/A (1) //Oneinteresting if

http://codeforces.com/contest/8/problem/B (2) //Sample vectors + set/or/array

http://codeforces.com/contest/12/problem/A (1) //Find mirror by middle

http://codeforces.com/contest/16/problem/A (1) //Easy check of chars

http://codeforces.com/contest/21/problem/A (2) //Easy but nasty iff imple

http://codeforces.com/contest/31/problem/B (2) //Boring imple

http://codeforces.com/contest/34/problem/C (3) //Easy string parsing

http://codeforces.com/contest/41/problem/C (2) //String parsing

http://www.spoj.com/problems/KPRIMESB/ (4)

http://www.spoj.com/problems/IITKWPCH/ (4) //NICE — on bits

http://www.spoj.com/problems/SUBSET/ (5) //VERY NICE — 3^10 (^2 but not exactly) (+ sorting)

https://www.hackerearth.com/practice/algorithms/dynamic-programming/bit-masking/practice-problems/algorithm/special-pairs-7/description/ (4) //NICE [Brute-force]

http://codeforces.com/contest/897/problem/D (4) //NICE! Back/Front

http://codeforces.com/contest/727/problem/C (2)

http://codeforces.com/contest/810/problem/D (4) //BS * 3 (same)

http://codeforces.com/contest/811/problem/D (4) //BFS — easy .. some ifs

http://codeforces.com/contest/835/problem/E (4) //NICE! Bitsets + Detect + XOR

http://codeforces.com/contest/844/problem/D (5) //NICE! Randomized algo

http://codeforces.com/contest/862/problem/D (4) //NICE! Find first + Binary Search

http://codeforces.com/contest/872/problem/D (4) //NICE! [no clue why it passed]

https://www.urionlinejudge.com.br/judge/en/problems/view/2652 (4) //Tree isomorphism

UVA 12489 //Tree

https://www.hackerrank.com/contests/hourrank-16/challenges/jenny-subtrees/problem

http://www.spoj.com/problems/DSUBTREE/ (5) //Isomorphism on trees (try all subsets)

http://www.spoj.com/problems/TREEISO/ (4) //Simple isomorphism of trees

http://codeforces.com/gym/101864 A //Observation

UVA 151

UVA 1394

UVA 440

3803 [LA]

https://www.urionlinejudge.com.br/judge/en/problems/view/1030

UVA 12912

UVA 13114

11351 UVA (2)

http://www.spoj.com/problems/CLSLDR/ (4) //Muchas queries — go DP

http://www.spoj.com/problems/WTK/ (Easy) Suggested by codeforrest

http://www.spoj.com/problems/DANGER/ (Easy) Suggested by codeforrest

http://www.spoj.com/problems/POCRI/ (Medium) Suggested by codeforrest

http://www.spoj.com/problems/NG0FRCTN/ (Medium) Suggested by codeforrest

http://www.spoj.com/problems/ADAPET/

UVA 12604

UVA 12467

UVA 11019

http://www.spoj.com/problems/NAJPF/ (4) //classical kmp — all patterns

http://codeforces.com/contest/808/problem/G (6) //with DP -harder

http://www.spoj.com/problems/ADAAPPLE/ [HLD][LCT works too]

http://www.spoj.com/problems/ADAVISIT/ [HLD]

http://www.spoj.com/problems/ADALICI/ [KTH Ancestor — FAST!]

http://www.spoj.com/problems/ADAORANG/

https://www.spoj.com/problems/COWGATH/ (5) //[VERY NICE][EULER][OFFLINE][SEGMENT]

https://codeforces.com/gym/102021 A //[IMPLEMENTATION][LCA]

http://codeforces.com/gym/101908/problem/L (5) //[NICE][HLD][FW]

http://codeforces.com/gym/101808/problem/K (5) //[NICE][IMPLEMENTATION][CYCLE]

http://www.spoj.com/problems/LCA/ //Easiest one — low constraints [practice]

http://www.spoj.com/problems/LCASQ/

http://codeforces.com/contest/916/problem/E (6) //[VERY NICE][SEG-TREE]//REROOT

http://codeforces.com/contest/911/problem/F (5) //[VERY NICE][LONGEST PATH]

https://devskill.com/CodingProblems/ViewProblem/141

UVA 12655

https://www.codechef.com/problems/PSHTTR

LightOJ 1162

Gym 100685G [2012-2013 ACM-ICPC, NEERC, Moscow Subregional Contest]

UVA 12533

https://www.codechef.com/problems/CLOSEFAR //But kinda more comples [ST]

http://codeforces.com/contest/733/problem/F 7

11354 UVA (4)

http://www.spoj.com/problems/POLICEMEN/ (3) //simple + small graph

http://www.spoj.com/problems/QTREE2/ (5) //very easy if bin. understrood

http://codeforces.com/contest/828/problem/F 7 // Differently MST / Outside

http://codeforces.com/contest/832/problem/D (5) //Classical + Depth /OR/ HLD +ST

http://www.spoj.com/problems/DRTREE/ (5) //NICE [finding ancestor + depths]

http://codeforces.com/problemset/problem/838/B (6) //VERY NICE [HLD + ET + ST]

http://www.spoj.com/problems/NTICKETS/ (4) //Maximum on path

http://www.spoj.com/problems/GRASSPLA/ (5) //HLD

http://codeforces.com/contest/855/problem/D (4) //VERY VERY BAD STATEMENT (not so bad problem)

http://codeforces.com/gym/101630 {L}(6) //[NICE][HLD or DSU][XOR] //Parenthessis

http://www.spoj.com/problems/ADASEED/ [HUNT]

http://www.spoj.com/problems/MC/

UVA 10192

UVA 531

LightOJ 1110

UVA 12747 //Perm

http://www.spoj.com/problems/XMEN/ //Perm

UVA 10405

UVA 12511 //Increasing

UVA 10635 //Increasing

10949 UVA (6) — Hunt or Bit

http://www.spoj.com/problems/MC/ (3) //Classical

http://www.spoj.com/problems/LCS0/ (7) //Bit

http://www.spoj.com/problems/ADAROADS/ [ONLINE][UPDATES][LCT]

http://www.spoj.com/problems/DYNALCA/en/ //DYNAMIC LCA

http://codeforces.com/gym/100460/problem/C

http://codeforces.com/gym/100960/problem/H

http://www.spoj.com/problems/DYNACON1/

http://codeforces.com/contest/892/problem/E (7) [VERY NICE]//By prices .. LCT

UVA 231

UVA 10131

2931 LA

http://www.spoj.com/problems/NDS/

UVA 481

http://www.spoj.com/problems/ELIS/

UVA 497

UVA 11790

http://www.spoj.com/problems/ALTSEQ/ 3 //solvable by FW in Nlog(N)

http://www.spoj.com/problems/VISIBLEBOX/ (4) //with multiset

http://www.spoj.com/problems/DOSA/ (5)

http://www.spoj.com/problems/CODERE3/ 3 //Low bounds LIS/LDS

http://www.spoj.com/problems/BRDGHRD/ 4 //lis (nondecreasing)

http://www.spoj.com/problems/GONESORT/ 4 //Permutation-lis + riddle statement

http://codeforces.com/contest/847/problem/B 4 //Multiple Lis's

http://codeforces.com/contest/67/problem/D (4) //[NICE][DOUBLE REMAP]

http://www.spoj.com/problems/ADAPATH/

http://www.spoj.com/problems/ADACITY/

http://www.spoj.com/problems/ADAPLNTS/

https://codeforces.com/contest/1198/problem/E (7) //[VERY NICE][HARD][KONIG][OBSERVATION]

URI 1330 (4) //[NICE][SIMPLE]

http://codeforces.com/gym/101873 F

http://codeforces.com/gym/101666 E //[NICE][GEOMETRY][BINARY SEARCH][PROBABILITY]

http://www.spoj.com/problems/MATCHING/ //Raw (no sauce)

http://codeforces.com/contest/116/problem/B (3) //Low cons. Can be done without algo

6234 — Tile Cut (LA)

10080 — Gopher II (UVA) //Easy — sympathic

11419 — SAM I AM (UVA) //Grid-Matching

http://codeforces.com/gym/101485 (Elementary Math — E) //Very nice principal [not that hard]

3673 — Black-White Grid (UVA) //Grid

12927 — Points Cover (UVA)

6851 — The Programmers (LA)

6887 — Book Club //NICE

6571 — It Can Be Arranged

12530 — Game of Tiles

http://codeforces.com/gym/100820 (Airport — A) //Nice one

http://codeforces.com/gym/100753 (Bounty Hunterr II — B) //VERY NICE — I refered multiple times to this principal

http://codeforces.com/gym/101408 (Cat vs Dog — C)

1171 — Knights in Chessboard (II) (LOJ) //Classical chess

12644 — Vocabulary

http://codeforces.com/gym/101047/problem/H

http://codeforces.com/problemset/problem/659/E

12972 — Cuban Challenge (UVA)

1201 — Taxi Cab Scheme (UVA)

12963 — Astragalus Nitidiflorus

6525 — Attacking rooks (LA)

3415 — Guardian of Decency (LA)

12159 — Gun Fight (UVA)

https://www.codechef.com/problems/CHEFYODA //Imho matching is not the crucial part here

12831 — Bob the Builder

http://codeforces.com/problemset/problem/831/D

11262 — Weird Fence

12549 — Sentry Robots

11138 — Nuts and Bolts

http://codeforces.com/contest/727/problem/D 4

11985 UVA (5)

http://www.spoj.com/problems/AMR12A/ (5) //VERY NICE goophers + bonus

http://www.spoj.com/problems/NITT4/ (4) //VERY NICE [Chessboard matching]

http://www.spoj.com/problems/SCPC11H/ (4)//NICE — Match those which fits inside

12045 UVA (4)

http://www.spoj.com/problems/ADAMONEY/

UVA 13298 — A Fibonacci Family Formula (4) //[NICE][CLASSICAL]

http://codeforces.com/gym/101628/problem/I (4) //[MODULAR][NICE][TRANSITION]

http://codeforces.com/gym/101845/problem/A

13284 Macarons (4) //[NICE][BITMASK][DP] Classical

http://codeforces.com/contest/147/problem/B (5) //[NICE][BS][GRAPHS]

http://codeforces.com/contest/107/problem/D (5) //[NICE][DP]

UVA 12653

LightOJ 1131

UVA — 12470

http://codeforces.com/problemset/problem/696/D

https://www.hackerrank.com/contests/mathemagic-bits/challenges/gp-on-fibonacci-matrix [accesable?]

https://www.hackerrank.com/contests/mathemagic-bits/challenges/degree-diameter-on-trees [accesable?]

LightOJ 1052

https://www.codechef.com/problems/KBIGNUMB

LightOJ 1160

LightOJ 1096

UVA 11486

http://codeforces.com/problemset/problem/718/C

LightOJ 1070

LightOJ 1132

http://codeforces.com/problemset/problem/621/E

Project Euler #114: Counting block combinations I

http://codeforces.com/problemset/problem/821/E

UVA 12593

https://www.codechef.com/AUG16/problems/SHAIKHGN //Not exactly but similar principle

11551 UVA (4)

11486 UVA (5)

10743 UVA (5) //A001169 [easy multi / hard to come with recurence]

http://codeforces.com/contest/821/problem/E (6) //Not trivial to come-up with matrix

http://www.spoj.com/problems/DCEPCA06/ (4) //NICE — 10x10 matrix

http://www.spoj.com/problems/GSWORDS/ (3) //NICE&EASY — 3-states "OO,OX,XO"

http://www.spoj.com/problems/TETRAHRD/ (4) //Easy + Sum

http://www.spoj.com/problems/NACCI/ (4) //Classical (N-Bonacci)

http://www.spoj.com/problems/JZPCIR/ (5) //VERY NICE: A137726

http://www.spoj.com/problems/ADAGROW/

http://www.spoj.com/problems/ADAFEAR/

https://www.urionlinejudge.com.br/judge/en/problems/view/1617 (4) //[BASIC]

13288 — Cordon Bleu (6) //[NICE][MATCHING]

http://codeforces.com/gym/100800 (Aqueduct Construction — A)

10806 — Dijkstra, Dijkstra.

12944 — Earthquake Disaster

12891 — Risk of Trading

https://www.codechef.com/problems/HOGON

http://codeforces.com/contest/863/problem/F (5) //VERY NICE

11613 UVA (6)

http://codeforces.com/contest/802/problem/C (8) //Nice but hard to see + negative

http://codeforces.com/contest/802/problem/N (5) //Easy but faster MCMF needed

http://codeforces.com/contest/818/problem/G (6) //NICE + MUCH Faster MCMF

http://www.spoj.com/problems/BNMT/ (7) //VERY NICE (some optimalisations needed + weird data set)

http://codeforces.com/contest/884/problem/F (6) //Alphabetical buckets

http://codeforces.com/contest/713/problem/C 7

http://www.spoj.com/problems/RMID2/ 4

http://www.spoj.com/problems/RMID/ 3 (as above just not so dynamic)

http://www.spoj.com/problems/EC_ESTA/ 4 //classical dynamic median

http://www.spoj.com/problems/DCEPCA09/ (6) //VERY NICE [MO +++ MEDIAN, MEAN, FREQ]

http://codeforces.com/contest/912/problem/E (5) //[VERY NICE][BS][2P][PRIMES]

http://codeforces.com/contest/888/problem/E (4) //NICE[EASY]

http://codeforces.com/contest/51/problem/E (6) //NICE[GRAPH][Cycles of length 5]

https://devskill.com/CodingProblems/ViewProblem/245

https://devskill.com/CodingProblems/ViewProblem/256

11851 UVA (5)

11465 UVA (5)

13207 UVA (4) //Straight-forward MIM

http://www.spoj.com/problems/COLOR_CC/ (4) //VERY NICE — div by partity (take lesser) → 8^6

http://www.spoj.com/problems/ADAUNIQ/ [Updates]

http://www.spoj.com/problems/ADANUM/

http://www.spoj.com/problems/ADAPEAR/

http://www.spoj.com/problems/ADAPHONE/

https://www.spoj.com/problems/MOZHSLS/ (5) //[VERY NICE]

http://www.spoj.com/problems/ADAFTBLL/ [Tree][Updates]

http://codeforces.com/gym/101879/problem/H (5) //[NICE][CLASSICAL][FREQUENCIES][FENWICK][BS]

http://www.spoj.com/problems/FREQUENT/

http://codeforces.com/contest/86/problem/D (4) //[NICE][CLASSICAL]

http://codeforces.com/contest/877/problem/F (6) //[NICE][NORMALIZE]

http://codeforces.com/problemset/problem/687/D

http://codeforces.com/problemset/problem/617/E

http://www.spoj.com/problems/DCEPCA09/

http://www.spoj.com/problems/COT2/

https://www.codechef.com/problems/DISTNUM3 //Tree + Update

https://toph.ws/p/distinct-dishting //Not sure if still working??

https://www.codechef.com/problems/CHEFNUMK

https://www.hackerearth.com/problem/algorithm/harry-gets-into-infy-1/description/

http://www.spoj.com/problems/COT/ (7) //ON TREE [but very tight TLE]

http://www.spoj.com/problems/GOT/ (5) //ON TREE

http://www.spoj.com/problems/CPAIR2/ (4) //MO + Fenwick [VERY NICE]

http://www.spoj.com/problems/HRSIAM/ (5) //With updates

http://www.spoj.com/problems/KDOMINO/ (4) //NICE — Frequencies

https://codeforces.com/contest/1187/problem/B (3) //[NICE]

13257 — License Plates UVA //Brute-Force 26^3 queries in O(1)

http://codeforces.com/contest/92/problem/C (3) //[VERY NICE]

LightOJ 1157

https://www.codechef.com/problems/ASTRING

http://www.spoj.com/problems/MAIN8_E/

http://codeforces.com/problemset/problem/701/C

http://www.spoj.com/problems/STRSEQ/ //+DP

http://codeforces.com/problemset/problem/762/C

http://codeforces.com/problemset/problem/724/D

http://www.spoj.com/problems/SUBSN/ //+BS

https://www.hackerrank.com/contests/world-codesprint-5/challenges/short-palindrome //+DP

http://www.spoj.com/problems/ADACROW

http://www.spoj.com/problems/ADAPARTY/

http://www.spoj.com/problems/ADAPARTI/

http://codeforces.com/gym/101908/problem/J (6) //[VERY NICE][STEINER][GEOMETRY]

http://codeforces.com/gym/101666 G //[NICE][BURTE FORCE][OBSERVATION][SUBSETS]

http://codeforces.com/contest/907/problem/E (5) //[VERY NICE][CLIQUE][DP]

http://codeforces.com/contest/114/problem/B (3) //[CLIQUE][BRUTE-FORCE]

http://www.spoj.com/problems/JOHNNY/ //Not exact — points

http://www.spoj.com/problems/TAKIN/ (3) //[KNAPSACK][RECURSION]

http://codeforces.com/contest/839/problem/E (5) //NICE! Max-Clique

7743 — Cliques (Similar to ADAPARTI) (8) //Parametrisation

7616 Counting Cliques (4) //[NICE][CLIQUES][ELIMINATING-SETS]

https://codeforces.com/contest/1181/problem/A (2) //[EASY][FORMULA][MODULO]

https://www.spoj.com/problems/PRADIPSUM/ (2) //[EASY][FORMULA]

UVA 10667 //Largest rectangle

UVA 10074 //Largest rectangle

UVA 836 //Largest rectangle

UVA 1330 //Largest rectangle

12192 UVA 5

http://codeforces.com/contest/729/problem/B 2

http://codeforces.com/contest/710/problem/C 4

11871 UVA 6

11617 UVA (3)

11573 UVA (4)

11499 UVA (5)

11230 UVA (4)

http://www.spoj.com/problems/JOCHEF/ (5) //NICE: Lagers rectange 0/1 O(N*M)

http://www.spoj.com/problems/ADAGCD/ [+STL]

http://www.spoj.com/problems/ADAHACK/

http://www.spoj.com/problems/ADADUNG/

http://www.spoj.com/problems/ADACAROT/

http://www.spoj.com/problems/ADACON/

http://www.spoj.com/problems/ADATAXES/

http://www.spoj.com/problems/ADADIG/

http://www.spoj.com/problems/ADASETS/

https://codeforces.com/contest/1175/problem/A (2) //[EASY][SYMPATHIC][DIVISION]

https://codeforces.com/contest/1203/problem/C (3) //[NICE][GCD]

https://devskill.com/CodingProblems/ViewProblem/553 (3) //[VERY NICE][SIMPLE]

https://devskill.com/CodingProblems/ViewProblem/560 (2)

https://codeforces.com/contest/1176/problem/B (2) //[MODULO][GREEDY]

https://codeforces.com/contest/1200/problem/C (4) //[VERY NICE][GCD][LCM]

https://codeforces.com/contest/1182/problem/A (2) //[EASY][DP]

https://atcoder.jp/contests/abc136/tasks/abc136_b (2) //[IMPLEMENTATION][CONVERSION]

https://codeforces.com/contest/1185/problem/A (1)

https://codeforces.com/contest/1198/problem/F (6) //[VERY NICE][RANDOM][FACTORISATION][PRIME][GCD]

https://codeforces.com/contest/1183/problem/B (2) //[EASY][FORMULA][MIN/MAX]

https://codeforces.com/contest/1187/problem/A (1) //[EASY][FORMULA]

https://codeforces.com/contest/1195/problem/B (2) //[EASY][GAUSS][BRUTE]

https://codeforces.com/contest/1189/problem/E (5) //[INVERSION][STL]

https://www.spoj.com/problems/CANPR/ (5) //[NICE][MOBIUS] Weird TC (weak?)

https://www.spoj.com/problems/OVISLARSUM/ (3) //[FORMULA][128]

https://www.urionlinejudge.com.br/judge/en/problems/view/2876 (6) //[VERY NICE][GCD][IE]

https://codeforces.com/gym/102058/problem/E (3) //[BRUTE-FORCE][GCD]

https://codeforces.com/gym/101972/problem/A (3) //[EASY][SIMULATION]

https://toph.co/p/pascals-triangle (2)

https://toph.co/p/big-factorials (1)

https://www.codechef.com/viewsolution/21428053 (4) //[SORTING][ANGLES][MATH][COSINUS]

http://codeforces.com/gym/101962 C

http://codeforces.com/gym/101808/problem/G (4) //[GCD][IF][LCM]

http://codeforces.com/gym/101666 L //[GREED][DP] Logarithms

http://codeforces.com/gym/101666 C //[NICE][GCD]

13287 — Shattered Cake (2) //Rectangle

http://codeforces.com/gym/101650 G //Graphs

http://codeforces.com/contest/934/problem/D (4) //Polynomials

8253 — Boss Battle LA

http://codeforces.com/contest/919/problem/E (5) //[MODULAR-MATH]

http://codeforces.com/contest/149/problem/B (3) //Base to 10

http://codeforces.com/contest/148/problem/B (3) //[SIMULATION](math or bs)

http://codeforces.com/contest/148/problem/A (2) //[EASY][SIEVE][BRUTE-FOCE][LCM][IE]

http://www.spoj.com/problems/JGTLE/ (3) //Sum reduction

http://www.spoj.com/problems/BAPM/ (3) //Simple power / Observe, rare colisions

http://codeforces.com/contest/911/problem/C (2) //[Observation][Iff (or brute-froce)]

http://codeforces.com/contest/133/problem/B (2) //Bases + implementation

http://codeforces.com/contest/129/problem/A (1) //Parity

http://codeforces.com/contest/124/problem/D (4)

http://codeforces.com/contest/125/problem/A (1) //mod/div simple — if

http://codeforces.com/contest/902/problem/D (4) //Polynomials / Fibonacci / Bitset

http://codeforces.com/contest/899/problem/D (4) //X99999 possibilities

http://codeforces.com/contest/899/problem/C (3) //[NICE][GREEDY KNAPSACK]

http://codeforces.com/contest/899/problem/A (1)

http://codeforces.com/contest/898/problem/A (1)

http://codeforces.com/gym/101620 {F}(4) //[IFS][INVERSE][CASES]

http://codeforces.com/contest/900/problem/D (4) //[NICE][DIVISORS][GCD][IE]

http://codeforces.com/contest/900/problem/B (2) //Cycles or Brute-force + Division

http://codeforces.com/contest/119/problem/A (2) //[EASY][GCD]

8014 — Birthday Pizza Party (4) //[NICE][OVERFLOW][LCM WITH SHIFT]

7629 — Powers (3) //One path is factorisation

8037 — Military Service (2) //Sample formula

8085 — Divisors (4) //[NICE][PRIMES/FACTORISATION/SIEVE]

6589 — Captain Obvious and the Rabbit-Man (7) //Sylvester's formula

6582 — Magical GCD (4) //[NICE] — Data structures works too

8000 — FizzBuzz (1)

https://devskill.com/CodingProblems/ViewProblem/421 (2) //6 buckets

http://codeforces.com/contest/93/problem/E (5) //[VERY NICE][DP][RECURSION]

http://codeforces.com/contest/86/problem/A (3) //[NICE] 50* is best (unless more digits)

http://codeforces.com/contest/83/problem/D (5) //[VERY NICE][PRIMES][BRUTE-FORE-2]

http://codeforces.com/contest/82/problem/A (2) //Simulation

http://codeforces.com/contest/74/problem/C (4) //gcd

http://codeforces.com/contest/76/problem/E (4) //Divide sumations [BF]

http://codeforces.com/contest/71/problem/C (3) //[EASY][NICE][BRUTE-FORCE][DIVISORS]

http://codeforces.com/contest/70/problem/A (2) //3^(N-1)

http://codeforces.com/contest/43/problem/C (2) //Moduly by 3 {0/2+min(1,2)}

http://codeforces.com/contest/50/problem/A (1) //[EASY]

http://codeforces.com/contest/61/problem/C (4) //Base conversion + roman

UVA 355 //bases conversion

2559 [LA] //Base conversion

https://www.codechef.com/problems/COPRIME3 //Cyka Möbius

http://www.spoj.com/problems/PSTR/ //Cyka Möbius

http://codeforces.com/problemset/problem/803/F //Cyka Möbius

https://devskill.com/CodingProblems/ViewProblem/23

http://codeforces.com/contest/731/problem/F 4

12031 UVA (8)

http://codeforces.com/contest/722/problem/F (8)

http://codeforces.com/contest/716/problem/C 4

http://codeforces.com/contest/711/problem/E (8)

http://codeforces.com/contest/710/problem/D (6)

13154 (UVA) 7

13166 (UVA) 5

11962 (UVA) 2

11718 UVA 3

11510 UVA (5)

11538 UVA (3) //good one — just math

11556 UVA (1)

http://codeforces.com/contest/757/problem/E (8)

http://codeforces.com/contest/758/problem/F (7)

11481 UVA (4)

11237 UVA (4) //Nice — seems like knapsbag but it it not

11155 UVA (4) //Almost as previous problem

11038 UVA (3) //counting digits on interval

http://codeforces.com/contest/763/problem/C (7)

11087 UVA (4) //Sums of two numbers divisible with <=500 (10^5)

http://codeforces.com/contest/678/problem/C 2 //LCM

http://codeforces.com/problemset/problem/665/F (8) //p^3 | p*q

http://www.spoj.com/problems/LCMSUM/ //Vzorec v knihovničce

http://www.spoj.com/problems/FRNDZND/ (2) // (size 1 == 1, else 0)

http://www.spoj.com/problems/EXPOR/ //bit-by-bit (+ formula)

http://www.spoj.com/problems/FACTDIV/ (5) //dyn-update of ans/factors GOOD

http://www.spoj.com/problems/PAIRDIV/ (6) //cyka möbius -_-

http://www.spoj.com/problems/FCDC/ (4) //keep factorized factorial

http://www.spoj.com/problems/NTHPRIME/ (7) // BS + NumPrime GOOD!!

http://www.spoj.com/problems/DIVFACT3/ (7) // Sieve 10^8 + sqrt search

http://www.spoj.com/problems/DIVFACT4/ (8) // Prime count

http://codeforces.com/contest/776/problem/C (4) //segments div. by number

http://codeforces.com/contest/776/problem/E (6) //vypsat cisla: f(N)=Phi(N),g(N)=N

http://www.spoj.com/problems/PHT/ (2) //easy BS (NN+2N) mby math?

http://www.spoj.com/problems/GCDEX/ (7) //OEIS A006579 — enough [well imp]

http://www.spoj.com/problems/APS/ (3) //just sieve + generate

http://www.spoj.com/problems/WPC5I/ (3)//fc: C[a]!=C[b]:F[a]^max(C[a],C[b])

http://www.spoj.com/problems/SPEC_SET/ N→N/k→N/k/k

http://www.spoj.com/problems/DCEPC11B/ (5) //Wilson't theorem!

http://www.spoj.com/problems/FACTMULN/ (5) //each f[i]/c[i] separately

http://www.spoj.com/problems/SPCM/ (4) //just factorisation + prime check (10^12)

http://www.spoj.com/problems/TWOGAME/ (5) //gcd == Power of 3 => YES

http://www.spoj.com/problems/MKEQUAL/ (2) //Chceck if sum is divisible by N

http://www.spoj.com/problems/TIPTOP/ (3) //sqrt(N)==N? NICE!!

http://www.spoj.com/problems/PSYCHON/ (4) // fast factorisation

http://www.spoj.com/problems/ENIGMATH/ (1) // swap and div by gcd

http://www.spoj.com/problems/SNGPG/ (3) // prime gen + check

http://codeforces.com/contest/795/problem/A (2) //brute-force

http://codeforces.com/contest/801/problem/E (6) //NICE! — Clique-DAG + inversion

http://codeforces.com/contest/798/problem/C (4) //GCD == at the beginning OR 2

http://codeforces.com/contest/803/problem/C (3) //Only "low" K and just divisors

10830 (4) //simple add 2→ sqrt(N) + their mirrors

http://codeforces.com/contest/817/problem/A (2) //check division + parity

13209 UVA (3) //Simple simulation of division (+states rememberance)

http://codeforces.com/contest/834/problem/C (4) //Has cube-root + both num divisible by cuberoot

http://codeforces.com/contest/837/problem/E (5) //Factorisation + GCD attributes

http://www.spoj.com/problems/SUMMATION/ (3) //Number contribution: 2^(N-1)

http://www.spoj.com/problems/SECTORS/ (4) //Odd len OR sum of odd indices == sum of even

http://www.spoj.com/problems/IITKWPCM/ (6) //VERY NICE — Gauss's generalisation of Wilsons Theorem

http://www.spoj.com/problems/UCV2013A/ (4) //N*(N^L-1)/(N-1)

http://www.spoj.com/problems/KIMO1/ (4) //NICE — Adding/Subing by modulus

http://www.spoj.com/problems/AFS2/ (4) //Sum of divisort (sqrt(N)) — (+128int)

http://www.spoj.com/problems/FUNNUMS/ (4) //Permutations (get ith + guess ith)

http://www.spoj.com/problems/MAY99_3/ (3) //GCD

http://www.spoj.com/problems/PUCMM334/ (3) //Classical hats problem

http://www.spoj.com/problems/LCPC11B/ (4) //Factorize + count all subsets

http://www.spoj.com/problems/THREENUMBERS/ (2) //EASY & NICE [lcm]

http://www.spoj.com/problems/GAMES/ (2) //EASY&NICE — Go discrete (by 10^k) → 10^k/GCD

http://www.spoj.com/problems/SUBSHARD/ (4) //dig*10^sufix*(choose sufix)*^Prefix [VERY NICE]

http://www.spoj.com/problems/INVDIV/ (6) //Sum of divisors function + factorisation [NICE]

http://www.spoj.com/problems/JNEXT/ (2) //EASY — Zahřívačka pro prváky

http://www.spoj.com/problems/TSHOW1/ (3) //NICE — Almost as binary repre with 5/6

http://codeforces.com/contest/859/problem/B (2) //Easy by iteration

http://codeforces.com/contest/861/problem/A (2) //5,2 division [EASY]

http://www.spoj.com/problems/ABA12D/ (4) //NICE — Formula for sum divisors Prod(Sum(fac-powers))

http://www.spoj.com/problems/MAIN74/ (3) //Fibo's

http://www.spoj.com/problems/NOSQ/ (3) //Sieve + Digit check

http://www.spoj.com/problems/SQUAREV1/ (3) //NICE (but dumb code limit)

http://codeforces.com/contest/597/problem/A (1) //Simple if+2*Divide

http://www.spoj.com/problems/STREETR/ (3) //Easy [GCD]

http://www.spoj.com/problems/HPYNOSII/ (3) //<=1000 after first move

http://www.spoj.com/problems/HPYNOS/ (1) //Same as above — 1 number

http://www.spoj.com/problems/IITD4/ (3) //Brute-force [sieve-like]

http://www.spoj.com/problems/GIRLSNBS/ (2) //Some easy formula

http://www.spoj.com/problems/GUESSTHE/ (2) //NICE [EASY][LCM]

http://codeforces.com/contest/867/problem/B (2) //NICE [observation][1 2]

http://www.spoj.com/problems/NDIVPHI/ (4) //NICE — Multiple of lowest primes [BIG-INT]

http://www.spoj.com/problems/NDIVPHI2/ (5) //NICE — Same as above [bigger constraints]

http://codeforces.com/contest/6/problem/A (1) //Triangle check (4 pts)

http://codeforces.com/contest/869/problem/B (1) //Answer is usually 0

http://codeforces.com/contest/9/problem/C (2) //Bases (2→ 10)

http://codeforces.com/contest/20/problem/B (2) //Ax^2+Bx+C=0 (find roots)

http://codeforces.com/contest/27/problem/E (5) //[VERY NICE]: Factorisation+Recursion

http://codeforces.com/contest/32/problem/C (3) //DSU works too

http://codeforces.com/contest/872/problem/C (3) //NICE — Compose of 4 (mby one 6 or 9)

http://codeforces.com/contest/876/problem/B (3) //Group by modulo

http://www.spoj.com/problems/ADABANKET/ //Observation (but Stoer-Wagner works too)

https://codeforces.com/contest/1194/problem/A (1) //[TRIVIAL]

https://www.spoj.com/problems/ARRTWIST/ (3)

https://www.spoj.com/problems/OPMODULO/ (3) //[NICE]Brute-force and observe

https://codeforces.com/gym/102001/problem/I (2) //[PARITY]

https://codeforces.com/gym/102001/problem/A (4) //[VERY NICE][FREQUENCY]

https://codeforces.com/gym/101991/problem/L (3) //[NICE][EASY][BITS]

https://codeforces.com/gym/102021 F //[NICE][SEQENCE]

https://www.codechef.com/problems/BUDDYNIM (3) //[OBSERVATION][NICE]

http://codeforces.com/gym/101962/problem/H (4) //[SEQUENCES][SIMULATION]

http://codeforces.com/contest/922/problem/C (3) //Note that K is always very low

http://codeforces.com/contest/912/problem/B (2) //Bits/XOR

http://codeforces.com/contest/911/problem/D (3) //[VERY NICE]

http://codeforces.com/contest/902/problem/E (5) //[VERY NICE] //LCT works too

7589 Rearranging a Sequence (3) //Print from back and then real

http://codeforces.com/gym/101630 {A}(6) //[NICE][STL]

http://codeforces.com/contest/122/problem/B (1) //just 4 or 7

http://codeforces.com/contest/116/problem/E (6) //[NICE][COMBINATORICS][FIND ANY]

http://codeforces.com/contest/892/problem/D (4) //NICE [SORTING]

http://codeforces.com/contest/897/problem/E (5) //[NICE][SET] //2 will beat all

7730 To begin or not to begin (3) //Parity

http://codeforces.com/contest/122/problem/D (4) //[NICE] Sweep /OR/ cycle

http://codeforces.com/contest/128/problem/D (6) //Normalize + Sweeps

https://codeforces.com/gym/101981 G //A000332

https://codeforces.com/gym/102001/problem/C //De Bruine

6591 — Bus (2) //2^N-1

12004 UVA 2

11273 UVA 5 //https://oeis.org/A001088

11077 UVA 3 //https://oeis.org/A094638

http://www.spoj.com/problems/VECTAR5/ 3 //https://oeis.org/A038721

http://www.spoj.com/problems/ESYRCRTN/ 2 //generate and see

http://www.spoj.com/problems/IITWPC4B/ 3 //http://oeis.org/A005044

http://www.spoj.com/problems/POLCONST/ (4) //A003401+Fermat Number (Prime)

http://www.spoj.com/problems/CUTCAKE/ (3) // pattern [1 22 333 4444 55555]

10872 UVA 3 //Alcuin's Sequence

http://www.spoj.com/problems/LOVINGPW/ (3) //A000788

http://www.spoj.com/problems/CBANK/ (3) //A000292 Tetrahedral numbers

http://www.spoj.com/problems/GUMATH2/ (4) //A000240 Modulo by MOD*2

http://www.spoj.com/problems/MATHII/ (4) //A006218 (Two formulas => sqrt(N))

http://www.spoj.com/problems/KOPC12B/ (4) //A002457 (factorial + factorial modular)

http://www.spoj.com/problems/YUMMY/ (4) //A006534

http://www.spoj.com/problems/ADV04B1/ (5) //A001850

http://www.spoj.com/problems/FLWRS/ (4) //A002464

http://www.spoj.com/problems/RANJAN02/ (3) //A024023

http://www.spoj.com/problems/BOMARBLE/ (2) //A000326

http://codeforces.com/contest/57/problem/C (4) //A045992

http://codeforces.com/contest/918/problem/A (1) //Fibo

http://www.spoj.com/problems/ADARAIN/

http://www.spoj.com/problems/ADARAINB/

http://www.spoj.com/problems/ADAROBOT/

https://www.spoj.com/problems/CLFLARR/ (3) //[NICE][EASY][QUEUE][STL]

https://codeforces.com/gym/102021 M //[VERY NICE][SPANNING]//LCA WORKS TOO

http://codeforces.com/gym/101840 I //[NICE][PREPROCESS]

http://codeforces.com/problemset/problem/816/B //Easier ST

11266 UVA (6) //slightly knapsack || [NICE]

http://codeforces.com/contest/761/problem/F (7)

http://www.spoj.com/problems/UPDATEIT/ (2) //basic method

13189 UVA (4) //simulation + sort queries

http://www.spoj.com/problems/HAYBALE/ (3) //Basic sum + sort (segment tree would work too)

http://codeforces.com/gym/101597/problem/H (6) //Offline 2D sum + geometry

https://www.spoj.com/problems/JUSTAPAL/ (6) //[VERY NICE][SA][RMQ]

https://www.spoj.com/problems/DRAGKING/ (4) //[CLASSICAL][DP]

https://codeforces.com/gym/101981 (5) //[NICE][SEGMENT][MANACHER][ZETA][SA]

https://codeforces.com/gym/101972/problem/F (3) //[EASY][OBSERVATION][GREEDY]

http://codeforces.com/gym/101628/problem/E (4) //[NICE][DP] //Easy

http://codeforces.com/gym/101864 J //[NICE][MANACHER]

http://codeforces.com/gym/101806/problem/Q (4) //[HASHING][PALINDROMIC-TREE]

http://codeforces.com/contest/897/problem/B (2) //Palindromic numbers [EASY][FIRST]

http://codeforces.com/contest/883/problem/H (3) //Make as least odd as possible

http://code-festival-2017-qualc.contest.atcoder.jp/tasks/code_festival_2017_qualc_c (3) //Similar to remove-dp, but greedy

http://code-festival-2017-qualc.contest.atcoder.jp/tasks/code_festival_2017_qualc_d (4) //DP with greedy thinking

http://codeforces.com/contest/59/problem/C (3) //Implementation [constructive]

UVA 13092 //manacher

http://www.spoj.com/problems/MSUBSTR/ //manacher

UVA 11888 //manacher

https://www.hackerrank.com/contests/101hack35/challenges/circular-palindromes //manacher

UVA 12378 //manacher

https://www.hackerrank.com/contests/world-codesprint-5/challenges/challenging-palindromes //SA

http://www.spoj.com/problems/NUMOFPAL/ //Palindromic Tree

http://codeforces.com/problemset/problem/245/H //# of palindromes [DP]

http://www.spoj.com/problems/ANAGR/ 2 //frequency + palindromes

http://www.spoj.com/problems/AMR12D/ (1) //Palindrome check //Zahrivacka pro prvaky

http://codeforces.com/problemset/problem/835/D //Hashing

http://codeforces.com/contest/137/problem/D (4) //[NICE][DP]

11019 UVA (5)

http://codeforces.com/contest/137/problem/B (1) //Frequency + size

http://codeforces.com/contest/136/problem/A (1) //Permutation cycles

http://codeforces.com/contest/844/problem/C 3 //NICE Permutations in array

http://codeforces.com/contest/48/problem/D (3) //NICE [frequency array]

http://codeforces.com/contest/56/problem/B (2) //Restore from 1 reverse [EASY]

http://codeforces.com/contest/122/problem/D (5) //NICE [BRUTE-FORCE]//ONLY BACK MATTERS

http://codeforces.com/contest/893/problem/F (6) //[VERY NICE][EULER TOUR]

http://codeforces.com/contest/813/problem/E (6) //Easy but hard data structure

https://codeforces.com/contest/893/problem/F //Suggested by phibrain

http://www.spoj.com/problems/ADAPLUS/

https://codeforces.com/contest/1175/problem/E (5) //[VERY NICE][LIFTING][PRIORITY]

https://codeforces.com/contest/1181/problem/C (4) //[VERY NICE][RMQ]

https://atcoder.jp/contests/abc136/tasks/abc136_d (4) //[NICE][PARITY]

https://codeforces.com/contest/1194/problem/B (3) //[IMPLEMENTATION][INDEXING]

http://www.spoj.com/problems/ADASQR/ [Monotone Queue]

https://toph.co/p/rio-and-inversion (5) //[NICE][INVERSIONS][PREFIX SUM][2D]

http://codeforces.com/gym/101801 I //[PREFIX SUM]

http://codeforces.com/gym/101889 L //[NICE][PREFIX SUM][BINARY SEARCH]

http://codeforces.com/contest/120/problem/D (3) //But maybe work naively ?!

http://codeforces.com/contest/48/problem/B (2) //2D Prefix Sum [BF prolly works too]

http://codeforces.com/problemset/problem/761/F

VA 10360 //2D Prefix Sum

UVA 983 //2D Prefix Sum

http://codeforces.com/contest/777/problem/C (4) //NICE

http://codeforces.com/contest/818/problem/C (4) //Prefix Sum

http://codeforces.com/contest/834/problem/B (2) //26 queries — NICE rozehrivacka pro prvaky

http://www.spoj.com/problems/RANGESUM/ (4) //NICE: Offline (delta) + Prefix Sum

http://www.spoj.com/problems/RANDG/ (3) //NICE [but too low bounds] [PrefixSum] [Try all indexes]

http://www.spoj.com/problems/HARSHAD/ (3) //Sieve + simple function

http://www.spoj.com/problems/PUCMM210/ (3) //Number theory (thinking not necessary)

http://www.spoj.com/problems/BCAKE/ (3) //Prefix sum of rectangle + N^4

http://www.spoj.com/problems/PAIRSUM/ (4) //VERY NICE — Prefix sum + Prefix PW sum

http://www.spoj.com/problems/MAIN111/ (3) //Sieve + Brute Force (answer in O(1))

http://www.spoj.com/problems/PLUSEVI/ (4) //NICE — There are not many of them

http://codeforces.com/contest/18/problem/C (2) //Prefix sum End==2*i

http://codeforces.com/contest/873/problem/B (2) //Search for same prefix (+/-1)

http://codeforces.com/contest/33/problem/C (4) //Prefix sum + Sweep from back + sweep from front

http://codeforces.com/contest/872/problem/B (3) //Sweep from both sides (RMQ works too)

http://www.spoj.com/problems/NTHPRIME/

http://www.spoj.com/problems/DIVFACT4/

http://codeforces.com/problemset/problem/665/F

https://www.codechef.com/problems/CNTPRIME

http://www.spoj.com/problems/SUMPRIM1/

http://www.spoj.com/problems/SUMPRIM2/ [NO — hard]

https://www.hackerrank.com/contests/projecteuler/challenges/euler010/problem //easy

http://www.spoj.com/problems/ADAGIFT/

https://www.spoj.com/problems/PRMFN/ (5) //[VERY NICE][GREEDY]

http://www.spoj.com/problems/PON/en/

http://www.spoj.com/problems/DAYOUT2C/en/ [EASY]

Project Euler #60: Prime pair sets

Project Euler #58: Spiral primes

Project Euler #131: Prime cube partnership

https://devskill.com/CodingProblems/ViewProblem/229

https://devskill.com/CodingProblems/ViewProblem/327

Gym 100753K [2015 German Collegiate Programming Contest (GCPC 15) + POI 10-T3]

Project Euler #130: Composites with prime repunit property

http://www.spoj.com/problems/ABA12A/ (3)

10871 UVA (3) //Easy — fermat not necessary

http://www.spoj.com/problems/POP1/ (4) //Fast primality testing (or somehow)

http://www.spoj.com/problems/POP2/ (5) //NICE — same as above (yet with ll)

http://www.spoj.com/problems/POP3/ (6) //same as above (yet with big)

http://www.spoj.com/problems/DCEPC203/ (6) //NICE [optimalisation]

http://www.spoj.com/problems/PRIMPERM/ (4) //NICE (next_perm + sieve)

https://codeforces.com/contest/1173/problem/E1 (5) //[NICE][DP]

https://codeforces.com/contest/1194/problem/F (6) //[NICE][COMBINATORICS][PREPROCESS]

http://codeforces.com/gym/101982 (5) K //[NICE][DP]

http://codeforces.com/gym/101845/problem/G (4) //[DP] Classical

http://codeforces.com/gym/101845/problem/M (3) //[NICE][OBSERVATION]

http://codeforces.com/gym/101726/problem/B (4) //[NICE][DP][BRUTE-FORCE]

https://www.devskill.com/CodingProblems/ViewProblem/470 (3) //Brute Force

8262 — Knockout Tournament (4) [LA] //[NICE][SIMULATION] //Might not be working on LA (but on CF y)

http://codeforces.com/contest/912/problem/D (4) //[VERY NICE][EXPECT][DIJKSTRA]

http://codeforces.com/contest/908/problem/D (5) //[DP][MATH][INVERSION]

7821 — Elections (4) //[EASY][DP]

http://codeforces.com/gym/101620 {G}(5) //[VERY NICE][DIJKSTRA][EXPECTED VALUE]

http://codeforces.com/contest/110/problem/D (4) //[NICE][COMBINATORICS]

http://codeforces.com/contest/108/problem/D (4) //[NICE][SIMPLE][COMBINATORICS]

7619 — Guessing the Dice Roll (5) //[NICE][AHO][MATRIX EXPO]

7998 — Election (3) //Math works too [probability][DP]

LightOJ 1104 //Birthday Paradox

Gym 101064K [2016 USP Try-outs] //Birthday Paradox

11762 UVA (5)

11427 UVA (5)

11348 UVA (2)

http://codeforces.com/contest/768/problem/D (4) //With DP

http://www.spoj.com/problems/IITWPC4J/ (4) //with DP

10828 UVA (5) //Nice problem but bad statemend: Expected value of visits MC

10777 UVA (4) //NICE — yet solvable with DP

http://codeforces.com/contest/839/problem/C (3) //NICE & Easy => Tree

http://www.spoj.com/problems/ZCR/ (3) //Easy (+DP)

http://www.spoj.com/problems/IITKWPCN/ (2) //Easy — Odd/Eve (black balls)

http://codeforces.com/contest/846/problem/F (5) // Expected number of unique elements

http://www.spoj.com/problems/BTCODE_H/ (4) //DP (but main GROW is idea)

http://codeforces.com/contest/867/problem/D (5) //VERY NICE [DP]

http://codeforces.com/contest/24/problem/D (5) //VERY NICE [DP]+[TIME]

http://codeforces.com/contest/28/problem/C (4) //VERY NICE [DP]

https://codeforces.com/contest/1175/problem/B (3) //[STACK]

https://www.codechef.com/problems/HPIRATES (4) //[VERY NICE][OBSERVATION][GRAPHS]

8255 — Dunglish LA //Finding all possibilities

http://codeforces.com/contest/915/problem/C (4) //[NICE][DP-works-too][GREEDY]

http://codeforces.com/contest/134/problem/B (4) //Number Theory

http://codeforces.com/contest/897/problem/C (4) //+Slightly [DP]

6585 — Draughts (4) //[NICE][BACKTRACK][DFS]

http://codeforces.com/contest/68/problem/D (5) //[NICE] Keep max and kill branches

UVA 536 //Tree from dfs

UVA 12347 //BST from preorder

http://www.spoj.com/problems/GOC11A/ 4

13170 UVA (7) //heavy implementation — but NICE!

10854 UVA (3) //if/else

http://codeforces.com/contest/31/problem/D (4) //[NICE] Brute-force by recursion

http://codeforces.com/contest/36/problem/B (2) //[NICE][SIMPLE]

https://www.spoj.com/problems/MOZPWS/ (4) //[NICE][IMPLEMENTATION][MQ]

https://codeforces.com/gym/101972/problem/G (4) //[NICE][SWEEP WORKS TOO]

http://codeforces.com/problemset/problem/514/D //+BS

http://codeforces.com/problemset/problem/872/B

http://www.spoj.com/problems/TNVFC1M/

https://devskill.com/CodingProblems/ViewProblem/19

http://codeforces.com/contest/713/problem/D 6

http://codeforces.com/contest/675/problem/E 5

http://www.spoj.com/problems/POSTERIN/ 5 //VERY NICE — Delete all minimas

http://www.spoj.com/problems/RPLN/ (3) //RMQ only

http://www.spoj.com/problems/CITY2/ (4) //RMQ + MAP [NICE][VAGUE STATEMENT]

http://www.spoj.com/problems/DIFERENC/ (4) //Solve separately (linear D&C)

http://codeforces.com/contest/863/problem/E (4) //OR some Queue / sorting

http://codeforces.com/contest/5/problem/C (4) //NICE — many other options

http://codeforces.com/contest/15/problem/D (5) //VERY NICE 2D RM [sliding-windw][monotone-queue]

http://codeforces.com/contest/873/problem/E (5) //[NICE][Brute-Force + RMQ]

http://www.spoj.com/problems/AROPE/ 4

http://www.spoj.com/problems/AROPE2/ 5 //same as above (+time)

http://www.spoj.com/problems/ADAPANEL/ [combinatorics]

13301 — Impossible Communication (4) //[CUTE][SAMPLE][OBSERVATION][EASY]

http://codeforces.com/problemset/problem/427/C proposed by unofficial10

http://codeforces.com/contest/894/problem/E (5) //[NICE][DP]

https://devskill.com/CodingProblems/ViewProblem/79

UVA 11838

UVA 247

UVA 13057

UVA 12645

UVA 11770

UVA 12926

UVA 11324

UVA 11709

UVA 12745

http://www.spoj.com/problems/TFRIENDS/ (4) //just scc size

http://www.spoj.com/problems/CAPCITY/ (4) //scc destination [WEAK TC]

http://codeforces.com/contest/22/problem/E (5) //[NICE][make it strongly connected][SRC>DST]

http://www.spoj.com/problems/ADABERRY/ [+TREAP]

https://codeforces.com/contest/1180/problem/E (6) //[VERY NICE]

https://codeforces.com/contest/1187/problem/D (5) //[VERY NICE][GREEDY][STACK]

https://toph.co/p/maintain-the-queue (5) //[NICE][QUEUE]

http://codeforces.com/gym/101992/problem/L (5) //[VERY NICE]

http://codeforces.com/gym/101982 F //[SWEEP][NORMALIZE][NICE][XOR]

http://codeforces.com/gym/101962/problem/I (4) //[BS]

http://codeforces.com/gym/101801 G //Two ST [SEQUENCE]

http://codeforces.com/gym/101879/problem/G (5) //Merge / Special

http://codeforces.com/gym/101741/problem/J (6) //[NICE][COMBINATORICS]

http://codeforces.com/contest/914/problem/D (5) //[NICE][GCD][LOG]

http://codeforces.com/contest/915/problem/E (5) //[VERY NICE][UNLIMITED]

http://codeforces.com/contest/145/problem/E (5) //[NICE]//Bit swap + subsequence

http://www.spoj.com/problems/ADAGF/

http://www.spoj.com/problems/ADATREE/

http://codeforces.com/contest/911/problem/G (7) //Segment tree over queries

http://codeforces.com/contest/895/problem/E (5) //[PRECISION]

http://codeforces.com/contest/52/problem/C (4) //Easy [MIN]+[INCREASE]

http://codeforces.com/contest/56/problem/E (5) //[NICE][NORMALIZE][MAX]

http://codeforces.com/contest/877/problem/E (5) //[VERY NICE][EULER TOUR TREE]

https://devskill.com/CodingProblems/ViewProblem/283

https://devskill.com/CodingProblems/ViewProblem/315

http://codeforces.com/problemset/problem/756/C

http://codeforces.com/contest/739/problem/C (8)

http://codeforces.com/contest/718/problem/C (8)

http://codeforces.com/contest/750/problem/E (7)

http://codeforces.com/contest/759/problem/C (7)

11165 UVA (5)

http://codeforces.com/contest/763/problem/E (8) //VERY NICE — [non-trivial]

http://www.spoj.com/problems/BGSHOOT/ (5) //normalize — then easy

http://www.spoj.com/problems/KGSS/ (4)

http://codeforces.com/contest/765/problem/F (7) //VERY NICE — CASCADE

http://www.spoj.com/problems/GSS1/ (5) //Idea — then easy

http://www.spoj.com/problems/KQUERYO/ (5) //Seg-tree of vectors

http://codeforces.com/contest/633/problem/G (8) //EulerTree+Seg+Bitset

http://www.spoj.com/problems/NAJ0001/ (7) //10^8 int — memory (and worked)

http://www.spoj.com/problems/PRMQUER/ (5) //2 segment trees + sieve

http://www.spoj.com/problems/EC_DIVS/ (5) //dunno if intended

http://www.spoj.com/problems/DCEPC11I/ (5) //NICE — 1,2,3,4,5,.. inc

http://www.spoj.com/problems/QUE2/ (4) //kth number

http://codeforces.com/contest/785/problem/E (6) //Seg+Treap [and faster]

http://codeforces.com/contest/786/problem/B (6) //+Dijkstra

13183 UVA (6) //Merge-Sort-Tree [dunno]

http://codeforces.com/contest/121/problem/E (7) //Dunno — done by vectorisation

http://codeforces.com/contest/803/problem/G (5) //VERY NICE!! — ST 10^9 + ST/RMQ 10^5

http://codeforces.com/contest/794/problem/F (7) //Digit by digit! (N*log(N)*100 )

http://codeforces.com/contest/811/problem/E (6) //VERY NICE — DSU (easier Timofey + animals)

http://codeforces.com/contest/817/problem/F (7) //10^18 + MEX ~~ NICE yet problematic

http://codeforces.com/contest/816/problem/B (3) //Or offline trick makes it easier

http://codeforces.com/contest/834/problem/D (5) //+Dynamic Programming | NICE

http://www.spoj.com/problems/SBO/ (5) //preLast→ last (-1), last→ now (+1) — VERY NICE

http://www.spoj.com/problems/GOODE/ (5) //NICE: Inversion + L-Mex

http://www.spoj.com/problems/CNTPRIME/ (3) //ST+Sieve (short range)

http://www.spoj.com/problems/SEGSQRSS/ (4) //NICE {weak data} ~~ SQRT works too

http://www.spoj.com/problems/MON2012/ (5) //NICE [Online][10^9 Range]

http://www.spoj.com/problems/PARSUMS/ (4) //But other approaches work too

http://www.spoj.com/problems/THRBL/ (4) //Simple SA — maximum on range <= A[a]

http://www.spoj.com/problems/HORRIBLE/ (3) //Totally classical

http://www.spoj.com/problems/MULTQ3/ (4) //NICE (interesting operation)

http://www.spoj.com/problems/PERMPATT/ (4) //NICE [minimum][+IDEA]

http://codeforces.com/contest/869/problem/E (5) //NICE — 2D [random][XOR]

http://codeforces.com/contest/19/problem/D (5) //NICE [+BS][+SET] {bs not necessary}

11885 UVA 7 //Previous problem requested for statement

11522 UVA 3 //Trick — low numbers only :P

http://www.spoj.com/problems/ADAPRIME/

https://devskill.com/CodingProblems/ViewProblem/577 (4) //[NICE][TWO POINTERS]

https://www.spoj.com/problems/EVENSEMIP/ (5) //[VERY NICE][SEGMENTED]

http://codeforces.com/gym/101982 H //[GOLDBACH]

http://codeforces.com/contest/114/problem/E (5) //[NICE][FAST THINGS NEEDED][SEGMENTED]

http://codeforces.com/contest/58/problem/B (3) //[NICE][GREEDY][LEAST PRIME FACTOR]

Project Euler #134: Prime pair connection //Segmented

11610 UVA (5)

11353 UVA (3)

http://www.spoj.com/problems/TDPRIMES/ (4)

http://www.spoj.com/problems/VECTAR8/ (3)

http://www.spoj.com/problems/NFACTOR/ (4)

http://www.spoj.com/problems/HS08PAUL/ (4) //simply generate

http://codeforces.com/contest/776/problem/B (3) //Easy — trict: PM-1/ELSE-2

http://www.spoj.com/problems/GGD/ (4) // N/lowestDiv*(lowestDiv-1)

http://codeforces.com/contest/822/problem/D (4) //DP + Lowest factor

http://www.spoj.com/problems/NGIRL/ (4) //Squares — Primes + BS == Easiest

http://www.spoj.com/problems/PTRI/ (5) //Very fast sieve necessary:/

http://www.spoj.com/problems/AFS/ (3) //Sum of divisort + DP

http://www.spoj.com/problems/BSPRIME/ (4) //Very fast sieve needed

http://www.spoj.com/problems/DCEPC505/ (4) //NICE — at most 10527450

http://www.spoj.com/problems/CUBEFR/ (3) //NICE — Sieve out k^3 numbers

http://www.spoj.com/problems/PRIMES2/ (8) //VERY NICE — Some hell-shit optimizing

http://codeforces.com/contest/26/problem/A (2) //Easy — many ways to solve it

https://codeforces.com/contest/1180/problem/C (4) //[MODULO][QUEUE]

https://codeforces.com/gym/102001/problem/F (4) //[NICE][GREEDY]

https://codeforces.com/gym/101991/problem/D (4) //[NICE][NORMALIZE][PREFIX]

https://codeforces.com/gym/102021 L //[NICE][JUST DO IT]

https://codeforces.com/gym/102021 D //Try one and see

https://codeforces.com/gym/101972/problem/K (3) //[EASY][STRINGS]

http://codeforces.com/gym/101962/problem/K (3) //[NICE] //Complexity

http://codeforces.com/gym/101650 A //[VERY NICE][TREAP][PROBABILITY]

http://codeforces.com/gym/101650 K //[NICE] //Perhaps weak TC

https://abc084.contest.atcoder.jp/tasks/abc084_c (3) //Brute-Force

http://codeforces.com/contest/908/problem/B (2) //[EASY][NICE]

http://codeforces.com/contest/141/problem/B (3) //[NICE][IF-PARTY]

7921 — Anticlockwise Motion (4) //Simulate in sqrt

7691 — Falling Apples (3)

7977 — The Key to Cryptography (2)

http://codeforces.com/contest/129/problem/B (2) //Graph

http://codeforces.com/contest/903/problem/B (2) //[NICE]

http://codeforces.com/contest/120/problem/C (1)

http://codeforces.com/contest/118/problem/A (1)

8012 — Voting Fraud (1)

http://codeforces.com/contest/897/problem/A (1) //BF — do as they say

7985 — Bumper-to-Bumper Traffic (4) //FINE — We have whole time-lapse

7988 Flow Shop (3) //Do as they say. Trivial but not bad.

7703 — Reading Digits (2) //Simple simulate what they ask for

http://codeforces.com/contest/893/problem/A (1) //Easy but nice

http://codeforces.com/contest/102/problem/B (2) //Do as they write — log-convergence

http://codeforces.com/contest/92/problem/A (1) //Way too easy

http://codeforces.com/contest/88/problem/C (3) //[NUMBER THEORY]

http://codeforces.com/contest/84/problem/D (4) //Priority queue by min*size

http://codeforces.com/contest/79/problem/A (1) //Simulate rules

http://codeforces.com/contest/879/problem/A (1) //Iterate day-by-day

http://codeforces.com/contest/879/problem/B (3) //Either at most N^2 or the biggest element [NICE]

http://codeforces.com/contest/879/problem/D (4) //[NICE][Array elimination]

http://codeforces.com/contest/46/problem/A (2) //[EASY][MODULO]

http://codeforces.com/contest/46/problem/B (3) //[EASY][SEARCH-EACH-QUERY]

http://codeforces.com/contest/55/problem/A (2) //Simple (long) simulation

http://codeforces.com/contest/60/problem/A (1) //Moving LR bounds

12187 UVA (2)

http://codeforces.com/contest/724/problem/C 5

http://codeforces.com/contest/746/problem/C 3

11093 UVA (2)

http://codeforces.com/contest/768/problem/C (4)

http://www.spoj.com/problems/WRONG/ (5) //VERY NICE — precalculate from back, then go from front

http://codeforces.com/contest/864/problem/C (4) //Not nice — just iffs

http://www.spoj.com/problems/WAGE/ (3) //Simple Game Of Life Modification

http://codeforces.com/contest/6/problem/C (2) //Simple simulate from both sides

http://codeforces.com/contest/9/problem/B (2) //Simulate what is given (+ doubles)

http://codeforces.com/contest/11/problem/B (3) //sqrt(X) [diff must be even]

http://codeforces.com/contest/30/problem/A (2) //Simply simulate process [-1000→ 1000]

http://www.spoj.com/problems/ADATOMAT/

http://www.spoj.com/problems/ADAUSORT/

http://www.spoj.com/problems/ADACUT/

http://www.spoj.com/problems/ADAHLIA/

https://codeforces.com/contest/1174/problem/B (3) //[OBSERVATION] Nice yet simple

https://codeforces.com/contest/1174/problem/A (2) //[EASY]

https://codeforces.com/contest/1203/problem/E (4) //[GREEDY][SIMPLE]

https://codeforces.com/contest/1203/problem/B (3) //[GREEDY][NICE]

https://codeforces.com/contest/1185/problem/D (4) //[BF][IMPLE][MATH]

https://codeforces.com/contest/1185/problem/C1 (3) //[GREEDY]

https://codeforces.com/contest/1197/problem/C (4) //[NICE][EASY][OBSERVATION]

https://codeforces.com/contest/1197/problem/A (3) //[SIMPLE][GREEDY][MATH]

https://codeforces.com/contest/1189/problem/B (3) //[EASY][OBSERVATION]

https://www.spoj.com/problems/SWAPDIFF1/ (4) //[CLASSICAL][INVERSIONS]

https://www.spoj.com/problems/SHINCARD/ (4) //[NICE]

https://www.spoj.com/problems/POTATOPL/ (4) //[NICE][GREEDY]

https://codeforces.com/gym/101991/problem/I (3)

http://codeforces.com/gym/101962/problem/M (4)

http://codeforces.com/gym/101726/problem/E (3) //[STRUCTURES][IMPLEMENTATION]

13282 Cakey McCakeFace (3) //Brute Force

8260 Installing Apps (4) //[NICE] //Sorting + some DP

http://codeforces.com/contest/922/problem/D (3) //[NICE][GREEDY][EASY]

http://codeforces.com/contest/920/problem/C (3) //[EASY] Sortable by parts

http://codeforces.com/contest/913/problem/D (4) //[NICE][BS][2P][FW]

http://codeforces.com/contest/149/problem/A (2) //Sorting|Greedy

http://www.spoj.com/problems/SEUG/ (2) //Bad statement

http://codeforces.com/contest/141/problem/A (2) //Or frequency

http://codeforces.com/contest/137/problem/E (4) //[NICE][PREFIX SUM MATCHING]

http://codeforces.com/contest/137/problem/C (4) //[NICE][FENWICK WORKS TOO]

http://codeforces.com/contest/136/problem/C (3) //Last to 1(2) |OR| first to INF

7601 — Football (3) //Greedy

7673 — What a Simple Research (2) //[EASY][IMPLE]

http://codeforces.com/contest/108/problem/B (2) //Easy & Adjacent

8025 — Stacking Cups (2) //Sorting+input

http://codeforces.com/contest/892/problem/A (2) //[EASY][SUM]

https://www.urionlinejudge.com.br/judge/en/problems/view/2290 (3) //Sort+check [fast]

http://codeforces.com/contest/81/problem/C (3) //MATH[Lesser=greater][comparator]

http://codeforces.com/contest/53/problem/D (3) //Bubble sort

http://codeforces.com/contest/58/problem/D (4) //[BUCKET][GREEDY][STRING]

UVA 10810 //INV

UVA 11858 //INV

http://codeforces.com/problemset/problem/645/B //INV

UVA 10327 //INV

http://www.spoj.com/problems/BUBBLESORT/ //INV

UVA 11495 //INV [GAME]

http://www.spoj.com/problems/CODESPTB/ //INV

UVA 13212 //INV

http://codeforces.com/problemset/problem/749/E //INV

12189 UVA (3)

12196 UVA (4)

http://codeforces.com/contest/731/problem/D 7

11925 UVA (4)

11979 UVA (3)

http://codeforces.com/contest/747/problem/D (4)

11890 UVA (4)

http://www.spoj.com/problems/KAOS/ (4) //INV — GOOD problem!!!!

http://www.spoj.com/problems/KSMALL/ (5) //fast sort /or/ quick-select

http://www.spoj.com/problems/RKS/ (3) //use map

http://www.spoj.com/problems/SPCJ/ (4) //reverse + go from back

http://codeforces.com/contest/785/problem/B (2) //last-first + vice versa

http://codeforces.com/contest/798/problem/D (4) //Take 1st then take best B of every pair (sort by A)

http://codeforces.com/contest/810/problem/B (2)

http://codeforces.com/contest/810/problem/C (3) //+Math

http://codeforces.com/contest/814/problem/A (1) //Pro prváky — but nice observation

http://codeforces.com/contest/817/problem/B (3) //Frequency of TOP 3

10769 UVA (3) //Sadly N^4 passes

13208 UVA (4) //Sort + Prefix Sum

13212 UVA (3) //Number of inversions

http://codeforces.com/contest/831/problem/C (3) //NICE ~ Check all "add" against first

http://codeforces.com/contest/831/problem/D (4) //Can be solved with BS+Max-Match

http://codeforces.com/contest/841/problem/C (3) //NICE — match greatest to lowest

http://codeforces.com/contest/845/problem/C (2) //EASY — pro prvaky

http://www.spoj.com/problems/HSHW/ (4) //Test every big/low pair + big/big low/low on +/-

http://www.spoj.com/problems/CODESPTB/ (3) //Count inversions [BASIC]

http://codeforces.com/contest/863/problem/B (2) //Sort and omit 2

http://www.spoj.com/problems/AMR10G/ (2) //Easy yet NICE

http://codeforces.com/contest/12/problem/C (2) //Very simple

http://codeforces.com/contest/16/problem/B (1) //[EASY]

http://codeforces.com/contest/22/problem/D (3) //Sort by begin + sweep

http://codeforces.com/contest/23/problem/C (3) //Take them by pairs + add last

http://codeforces.com/contest/24/problem/B (3) //Simple follow the rules

http://codeforces.com/contest/27/problem/B (3) //Compare number of victories

http://codeforces.com/contest/27/problem/C (4) //[NICE] Find next bigger/lesser (sort)

https://www.urionlinejudge.com.br/judge/en/problems/view/2683 (3) //[BASIC][MAXIMUM]

http://codeforces.com/contest/908/problem/F (5) //[VERY NICE] //Not exactly MST but similar[GREEDY]

http://codeforces.com/contest/125/problem/E (5) //[BS]

http://codeforces.com/contest/76/problem/A (4) //[VERY NICE] Sort by A and KEEP spanning + one edge

LA 6622 — Absurdistan Roads (4) //Plus one edge

UVA 12176

UVA 10600

UVA 10724

https://www.hackerrank.com/contests/june-world-codesprint/challenges/johnland

UVA 11710

Gym 101252C [2014-2015 CT S02E05: Codeforces Trainings Season 2 Episode 5 — 2009-2010 ACM-ICPC]

Gym 101047I [2015 USP Try-outs][HARD]

UVA 11183 [Directed]

LightOJ 1101

https://www.codechef.com/problems/CHEFELEC

UVA 10307

http://codeforces.com/problemset/problem/598/D

http://codeforces.com/problemset/problem/32/C

http://codeforces.com/problemset/problem/744/A

https://devskill.com/CodingProblems/ViewProblem/344

908 — Re-connecting Computer Sites [UVA]

1208 — Oreon [UVA]

1235 — Anti Brute Force Lock [UVA]

10034 — Freckles [UVA]

11228 — Transportation system [UVA]

11631 — Dark roads [UVA]

11733 — Airports [UVA]

11747 — Heavy Cycle Edges [UVA]

BLINNET SPOJ (3)

11183 UVA (4) //Directed [need to know algo!]

http://www.spoj.com/problems/ULM09/ (3) //Sum-Kruskal

http://www.spoj.com/problems/IITKWPCG/ (4) //VERY NICE [log instead of price]

http://codeforces.com/contest/17/problem/B (3) //Spanning tree [no dsu]

LightOJ 1074

UVA 1171

UVA 11478

UVA 12768

11478 UVA (5)

https://codeforces.com/contest/1199/problem/D (4) //[NICE][SIMPLE IMPLE]

https://www.spoj.com/problems/ZING01/ (5) //[VERY NICE][STRING][SEGMENT]

http://codeforces.com/gym/101889 D //[NICE][STL]

http://codeforces.com/contest/916/problem/D (6) //[NICE][BS][BINARY-LIFTING]

12003 UVA 7

11990 UVA (5)

http://www.spoj.com/problems/GIVEAWAY/ (7) //SQRT + BS > [or Seg+Trie]

http://codeforces.com/contest/786/problem/C (5) //Nsqrn (bg) + sqrSegs (end)

http://codeforces.com/contest/840/problem/D (5) //NICE — Either frequent OR brute-force

http://codeforces.com/contest/13/problem/E //VERY NICE [SQRT-BLOCK UPDATE/JUMP]

http://codeforces.com/contest/85/problem/D (4) //NICE [ST shall work too]

http://www.spoj.com/problems/ADABASET/ [IO-testing][ARRAY]

http://www.spoj.com/problems/ADALIST/ [ROPE]

http://www.spoj.com/problems/ADAFIELD/ [SET]

http://www.spoj.com/problems/ADAQUEUE/

http://www.spoj.com/problems/ADAFRIEN/

https://www.spoj.com/problems/REDARR2/ (4) //[NICE][PQ]

https://www.spoj.com/problems/MINSTOCK/ (3) //[EASY][MAP]

http://codeforces.com/gym/101864 F //[SET]

http://codeforces.com/contest/920/problem/B (3) //[NICE][QUEUE][SIMPLE]

http://codeforces.com/contest/911/problem/E (4) //[NICE][STACK][SET]

http://codeforces.com/contest/909/problem/D (4) //[VERY NICE][SIMULATION][GROUP]

http://codeforces.com/contest/899/problem/E (4) //[VERY NICE][SET]

https://arc087.contest.atcoder.jp/tasks/arc087_a (2) //Map

http://codeforces.com/contest/903/problem/C (2) //Map

http://codeforces.com/contest/900/problem/C (3) //[NICE][SET]

http://codeforces.com/contest/112/problem/A (1) //tolower [trivial]

3396 — Alphabetics (2) //Getline, letters identification

http://codeforces.com/contest/81/problem/A (2) //Stack OR string

http://codeforces.com/contest/78/problem/A (1) //fgets + imple

http://codeforces.com/contest/69/problem/E (3) //NICE [2POINTERS][SET][MAP]

http://www.spoj.com/problems/RMID/ //Dynamic Median

http://www.spoj.com/problems/RMID2/ //Dynamic Median

http://codeforces.com/problemset/problem/713/C //Dynamic Median

http://www.spoj.com/problems/EC_ESTA/ //Dynamic median

http://codeforces.com/contest/799/problem/B (2) //EASY — MAP

http://codeforces.com/contest/808/problem/D (3) //MAP

10887 (2) //string + map

10730 (3) //Easy with hash-map

http://codeforces.com/contest/821/problem/C (3) //STACK (vector) Nice+Easy

http://www.spoj.com/problems/SOLVEIT/ (3) //Set + lower_bound

http://www.spoj.com/problems/IITKWPCA/ (2) //Set + getline

http://codeforces.com/contest/849/problem/D (5) //Queue

http://www.spoj.com/problems/CRAN02/ (4) //Map (+Math)

http://www.spoj.com/problems/MAX_NUM/ (4) //Queue (possibly multiple ways)

http://www.spoj.com/problems/SID/ (5) //Sort + Vector (or similar) [strict TLE]

http://www.spoj.com/problems/RPLD/ (2) //Map of sets

http://codeforces.com/contest/861/problem/D (4) //unordered map of sets

http://www.spoj.com/problems/FACEFRND/ (2) //Set or Bitset

http://www.spoj.com/problems/HACKRNDM/ (3) //Easy — map

http://codeforces.com/contest/847/problem/K (4) //NICE Map+Queue

http://codeforces.com/contest/855/problem/A (1) //set

http://codeforces.com/contest/4/problem/C (2) //map+string

http://codeforces.com/contest/5/problem/E (6) //iffs + RMQ+BS+SET [or other sol]

http://codeforces.com/contest/44/problem/A (1) //Set + pair

http://codeforces.com/contest/45/problem/C (4) //NICE — Handling with sets

http://codeforces.com/contest/918/problem/B (2) //[MAP] //TLDR

https://codeforces.com/contest/1189/problem/A (2) //[OBSERVATION]

https://codeforces.com/contest/1194/problem/C (3) //[EASY][FREQUENCY][2POINTERS]

https://www.spoj.com/problems/MAGSUB1/ (3) //[EASY][SYMPATHIC][COMBINATORICS]

https://www.urionlinejudge.com.br/judge/en/problems/view/2866 (1) //Reverse

https://codeforces.com/gym/101972/problem/H (3) //[NICE][PREPROCESS]

http://codeforces.com/contest/909/problem/A (1) //Lexicographical comparision [EASY]

7948 Periodic Strings (2) //Brute-force

7892 — Game of Matchings (6) //No idea — heuristic works — but seems to be nice

8017 — Mancunian and Sonu Generate Strings (5) //[NICE][DP]//+Something: Trie/SA/SET...?

http://codeforces.com/contest/890/problem/D (4) //[NICE][SET][SORTING][26][BRUTE-FORCE]

http://codeforces.com/contest/43/problem/B (2) //Frequency

http://codeforces.com/contest/50/problem/B (2) //Frequency + Power

http://www.spoj.com/problems/MINMOVE/ (3) //Minimal lexicographical rotation

http://www.spoj.com/problems/BWHEELER/ //Burrows Wheeler

http://www.spoj.com/problems/EDIST/ //Edit Distance

3189 LA //Edit Distance

https://www.hackerrank.com/contests/morgan-stanley-2015/challenges/minimum-transformation-cost/problem //Edit Distance

http://codeforces.com/gym/101492/problem/L //Laevenstein Distance

UVA 13068 //Lexicographically lowest rotation

2755 [LA]//Lexicographically lowest rotation

LightOJ 1073 //Lexicographically Shortest Superstring

http://codeforces.com/contest/762/problem/C 5

http://www.spoj.com/problems/LCS0/ 10 //LCS

http://www.spoj.com/problems/IITWPC4H/ 2 //Frequence array

13186 UVA (6) //Bitset + Trie ~ NICE [6-7 mby?]

http://codeforces.com/contest/798/problem/B (2) //Brute-force .. pro prváky

10745 UVA (4) //Frequency (N^2 possible if efficient!!)

http://codeforces.com/contest/822/problem/B (2) //Easy pro prvaky (slightly imple.)

http://codeforces.com/contest/828/problem/C (4) //+Sorting (process only necessary!)

http://codeforces.com/contest/832/problem/B (3) //Naive compare back+front [+freq]

http://www.spoj.com/problems/STC04/ (5) //Next + pairs O(N*26) [frist look O(26^2*N)]

http://www.spoj.com/problems/IITKWPCJ/ (4) //GCD or HASHING

http://www.spoj.com/problems/SUBSN/ (4) //Next (NICE — bad input):

http://www.spoj.com/problems/BOGGLE/ (2) //EASY [MAP][STREAM]

http://www.spoj.com/problems/MAIN8_E/ (4) //VERY NICE — Next function

http://www.spoj.com/problems/STRMATCH/ (3) //Nice matching, yet low constraints on "N"

http://www.spoj.com/problems/FINDSR/ (3) //Clever bruteforce works here (NlogN)

http://codeforces.com/contest/39/problem/J (2) //Simple iteration over string

http://codeforces.com/contest/876/problem/E (4) //Compare from back + make fail-pairs

http://www.spoj.com/problems/ADAPHOTO/ [or hashing after turboanalisis]

http://www.spoj.com/problems/ADASTRNG/

https://codeforces.com/contest/1202/problem/E (5) //[NICE][OBSERVATION][RMQ]

https://codeforces.com/gym/101991/problem/E (6) //[VERY NICE][RMQ]Prolly an easier alternative

https://toph.co/p/distinctness (6) //[VERY NICE][SET][LCP][RMQ]

http://codeforces.com/gym/101889 M //[VERY NICE][OBSERVATION]

http://codeforces.com/gym/101840 B //[NICE][ST][BIT][LCP]

http://codeforces.com/contest/129/problem/D (4) //[NICE]//Suffix Automaton / Brute Force works too

http://codeforces.com/contest/123/problem/D (5) //[NICE][RMQ][D&C]

8086 Substring Sorting (7) //[VERY NICE][RMQ][BS][PST]

7702 — Castle //6 [VERY NICE][RMQ][BS][FW]

7701 — Favorite music //8 [VERY NICE][RMQ][SEARCH][OPTI] //WRONG TIME-LIMIT==OPTI

https://www.urionlinejudge.com.br/judge/en/problems/view/1530 //7 [VERY NICE][RMQ][SET][OFFLINE]

https://www.urionlinejudge.com.br/judge/en/problems/view/2000 (5) //Basic disubstr counting

UVA 760 //LCS

UVA 1227 //LCS

http://www.spoj.com/problems/LCS/en/ //LCS

UVA 11512

7502 [LA]

Gym 100923D [2015 ACM National Contest Romania — Round 1]

UVA 1254

UVA 12191

UVA 12206

https://www.codechef.com/problems/INSQ16F

3943 LA

UVA 11107

UVA 12974

UVA 10526

Davos and Reading [INSOMNIA] //Awesome problem but can't find link [hard] — non of regular judges

UVA 12338

https://devskill.com/CodingProblems/ViewProblem/328

12191 UVA 5

SARRAY SPOJ 3

4513 LA 6

http://www.spoj.com/problems/LCS2/ 7 // must be linear (SA+LCP+MQ)

http://codeforces.com/contest/802/problem/I 7 //NICE! SA+LCP+(Segmentree/queue)

http://www.spoj.com/problems/LONGCS/ //5 LCS of multiple strings (NICE)

http://www.spoj.com/problems/SUBLEX/ //5 VERY NICE: Kth substring

http://codeforces.com/contest/873/problem/F //6 VERY NICE: SA+Histogram

http://codeforces.com/contest/30/problem/E //7 VERY NICE: [many other sols: Manach/KMP/HASH...]

6856 — Circle of digits //7 [VERY NICE]

LightOJ 1146

Gym 101482G [2014-2015 Northwestern European Regional Contest (NWERC 2014)]

Gym 101309D [2010-2011 ACM-ICPC Northeastern European Regional Contest (NEERC 10)]

UVA 13010 //+Dijkstra

2015-2016 CTU Open Contest: Chasing the Cheetah

12197 UVA (4)

http://www.spoj.com/problems/KOPC12A/ (4) //TS (sadly brute-force works too N^2)

https://codeforces.com/gym/102058/problem/A (5) //[NICE][2TIMES][PRIORITY]

UVA 11686

LightOJ 1034

UVA 10305

124 — Following Orders [UVA]

200 — Rare Order [UVA]

872 — Ordering [UVA]

11060 — Beverages [UVA]

http://codeforces.com/contest/765/problem/E 5

http://codeforces.com/contest/770/problem/C 4 //reduce + toposort

http://codeforces.com/contest/825/problem/E 4 //Toposort from biggest/backward

http://www.spoj.com/problems/CODESPTI/ (6) //VERY NICE — Hard/Weak children

http://codeforces.com/contest/47/problem/B (2) //[EASY][Toposort on 3 elements]

http://codeforces.com/contest/909/problem/E (4) //[NICE][BFS][RECURSION]

https://codeforces.com/contest/1181/problem/D (5) //[VERY NICE][SORTING][OFFLINE]

https://www.hackerrank.com/challenges/find-the-running-median/problem (4) //[NICE][HEAPS]

http://codeforces.com/gym/101992/problem/M (4) //[NICE][OFFLINE][SORTING]

http://codeforces.com/gym/100112 C //[VERY NICE]

http://codeforces.com/gym/101864 B //[NICE] Lesser than

http://codeforces.com/contest/899/problem/F (5) //[VERY NICE][DATA STRUCTURE] (FW or Treap)

http://codeforces.com/contest/879/problem/E (6) //[VERY NICE][Making somponents]

http://www.spoj.com/problems/ADAAPHID/ [or clever fenwick][or SQRT-tree]

http://www.spoj.com/problems/ADACROP/

http://codeforces.com/contest/762/problem/E 6

http://www.spoj.com/problems/COUNT1IT/ 5

http://www.spoj.com/problems/IITWPC4D/ 4 //From end — pick i-th + del i-th

http://www.spoj.com/problems/ALLIN1/ 4 //Typical treap operations

http://codeforces.com/contest/847/problem/D 5 //Prolly overkill — VERY NICE

http://codeforces.com/contest/863/problem/D 4 //Not desired solution

http://www.spoj.com/problems/KOILINE/ (4) //VERY NICE — Iterate from back — get+remove

http://www.spoj.com/problems/TWIST/ (5) //NICE: Reverse

http://www.spoj.com/problems/MEANARR/ (5) //VERY NICE! [POLICY][SHORT]

http://www.spoj.com/problems/ADATOMEL/

https://codeforces.com/contest/1189/problem/D1 (4) //[OBSERVATION]

http://codeforces.com/contest/913/problem/B (2) //Simple check

http://codeforces.com/contest/894/problem/D (5) //[NICE][MERGING][BINARY]

http://codeforces.com/contest/746/problem/G 5

http://codeforces.com/contest/750/problem/F 9

http://www.spoj.com/problems/RTREE/ 3 //longest path tree — query

13175 UVA (2) //something like preorder build

http://codeforces.com/contest/796/problem/C (3) //Just counting — inc by at most 2

http://codeforces.com/contest/797/problem/D (4) //VERY NICE — sort + D&C all

http://codeforces.com/contest/805/problem/E (4) //NICE — Treewidth coloring (greedy)

http://codeforces.com/contest/828/problem/D (3) //Star construction

http://www.spoj.com/problems/TREEDEGREE/ (3) //Degree from euler tree

http://www.spoj.com/problems/UCV2013J/ (3) //Find what is leaf in Binary Tree

http://www.spoj.com/problems/GCPC11J/ (3) //Finding ceter

http://codeforces.com/contest/34/problem/D (3) //Simple reconstruction + DFS

http://www.spoj.com/problems/ADASALES/

https://codeforces.com/contest/1187/problem/E (5) //[VERY NICE][DFS]

http://www.spoj.com/problems/PT07X/ (4) //Classical- VC on tree [NICE]

http://codeforces.com/contest/81/problem/E (6) //[NICE][PSEUDOFOREST REDUCTION]

http://codeforces.com/contest/61/problem/D (4) //dfs-only might works too

LA 6631 — Jingle Balls (4) //[NICE][SIMPLE]

https://www.codechef.com/problems/TRANDED //By sahil070197

13089 — Golden Coins (UVA)

http://codeforces.com/problemset/problem/855/C

http://codeforces.com/problemset/problem/718/D

https://www.codechef.com/problems/TWOCOINS

https://www.hackerrank.com/contests/101hack35/challenges/road-maintenance/problem

7649 — Performance Review (LA)

http://codeforces.com/problemset/problem/741/D

http://codeforces.com/problemset/problem/592/D

https://www.codechef.com/problems/TOMJERGA

http://codeforces.com/problemset/problem/814/D

1220 — Party at Hali-Bula (UVA)

https://www.hackerrank.com/contests/june-world-codesprint/challenges/r-tree-decoration/problem

12452 — Plants vs. Zombies HD SP (UVA)

http://codeforces.com/problemset/problem/735/E

https://www.codechef.com/problems/COLTREE

12466 — Ancestors (UVA)

6829 — Intrepid climber (LA)

https://www.hackerrank.com/contests/101hack35/challenges/jeanies-route

12257 — The Queue (UVA)

http://codeforces.com/problemset/problem/805/F

http://codeforces.com/problemset/problem/763/D

1218 — Perfect Service

3346 — Perfect Domination on Trees (same as above -_-)

12093 — Protecting Zonk

10859 — Placing Lampposts

http://codeforces.com/problemset/problem/23/E //NICE [but requires big int]

http://codeforces.com/problemset/problem/14/D (5) //NICE [sorting-one][2DFS]

http://www.spoj.com/problems/TWOPATHS/ (6) //VERY NICE Same as above ~ bigger constraints

http://codeforces.com/contest/868/problem/E (8) //VERY NICE — HARD — on tree

https://www.spoj.com/problems/XORX/ (4) //[NICE][BASIC][PREFIXXOR]

http://codeforces.com/contest/888/problem/G (5) //NICE[BIT-BY-BIT D&C]

http://codeforces.com/contest/842/problem/D //Proposed by usernameson

http://codeforces.com/problemset/problem/706/D

https://www.hackerrank.com/contests/w8/challenges/black-box-1

https://csacademy.com/contest/round-42/task/xor-submatrix/

http://codeforces.com/contest/714/problem/C 5

http://www.spoj.com/problems/SUBXOR/ (4)

http://codeforces.com/contest/817/problem/E (5) //Classical — remember sum! NICE!

http://codeforces.com/contest/37/problem/C (4) //NICE — Prefix dictionary [or math]

http://www.spoj.com/problems/ADAINDEX/

http://codeforces.com/gym/101628/problem/K (5) //[NICE][IMPLEMENTATION]

8015 — Alice and Bob play Contact (5) //[VERY NICE] 1stBob

2642 [LA]

UVA 10860

UVA 10295

UVA 13186 //+Bitset

UVA 1123

UVA 12506

UVA 11539

UVA 1142

UVA 12359

UVA 10282

11732 UVA (5)

11539 UVA (5)

11488 UVA (4)

http://www.spoj.com/problems/TRYCOMP/ (4)

10860 UVA (4) //DP + Trie [nice — slightly generic]

http://www.spoj.com/problems/DICT/ (4) //Sample trie — but slightly weak/wrong data-set

https://www.urionlinejudge.com.br/judge/en/problems/view/2810 (5) //[NICE][DOUBLE]

Gym 100818E [2015-2016 ACM-ICPC Southeastern European Regional Programming Contest (SEERC 2015)]

3725 [LA]

UVA 10496

Gym 101020H [2015 Syrian Private Universities Collegiate Programming Contest] N!

LightOJ 1057

UVA 11643 //[NICE][BFS]

3305 [LA] //On plane

10937 UVA (4) //find '!' / BFS / TSP — NICE!

10944 UVA (4)

10818 UVA (5) //Easy — but not-easy implementation: ++Dijkstra [LEX!]

http://www.spoj.com/problems/A_W_S_N/ (4) //BFS + TSP (path) — NICE

http://www.spoj.com/problems/ADAFENCE/ [Multiple Pointers]

http://www.spoj.com/problems/ADAPLANT/

https://codeforces.com/contest/1175/problem/C (4) //[NICE][GREEDY]

https://codeforces.com/contest/1203/problem/D1 (4) //[VERY NICE][STRINGS][PREPROCESS]

https://codeforces.com/contest/1203/problem/D2 (5) //[VERY NICE][STRINGS][PREPROCESS]

https://codeforces.com/contest/1186/problem/C (4) //[VERY NICE][BITS][OBSERVATION]

https://www.spoj.com/problems/MOZHCAN/ (5) //[VERY NICE]

http://codeforces.com/gym/101864 L //Static Size [SORTING]

Dev Skills-499: Closest Pair Point (4) //[NICE][GEOMETRY][STRUCTURES]

http://codeforces.com/contest/919/problem/C (3) //Similar — simple sweep [EASY]

http://codeforces.com/contest/144/problem/C (3) //[NICE][FREQUENCY][STRINGS]

http://codeforces.com/contest/895/problem/B (3) //[OR BS]

http://codeforces.com/contest/84/problem/B (2) //EASY //ll

http://codeforces.com/contest/79/problem/C (4) //NICE — [STRINGS][SET][COMPARE]

http://codeforces.com/contest/746/problem/F 6

11436 UVA (5)

http://codeforces.com/contest/760/problem/D 4

11386 UVA (4)

http://www.spoj.com/problems/WOWSUBSTR2/ 3

http://www.spoj.com/problems/ARRAYSUB/ 4

http://www.spoj.com/problems/CODFURY/ 3 //easy — ukazkove

http://codeforces.com/contest/769/problem/B 3 //sort + TP

http://codeforces.com/contest/814/problem/C 4 //NICE — maybe some DP +/-

http://www.spoj.com/problems/CRAN04/ 4 //NICE — (more or less) 3 pointers

http://www.spoj.com/problems/OPCPIZZA/ 3 //NICE [EASY] [AGAINS EACH OTHER]

http://www.spoj.com/problems/ALIEN/ (3) //Classical

http://www.spoj.com/problems/HOTELS/ (3) //Classical & Easy

http://www.spoj.com/problems/KOIREP/ (4) //VERY NICE — N buckedt find mid diff

http://codeforces.com/contest/6/problem/E (4) //NICE — Multiset

http://codeforces.com/contest/873/problem/C (3) //NICE — M times 2P tenchique

UVA 1480

http://www.spoj.com/problems/ILKQUERY/

http://codeforces.com/contest/840/problem/D //Proposed by GreenGrape

https://www.codechef.com/problems/CHSTR //Proposed by Apptica

http://www.spoj.com/problems/SUFEQPRE/

http://codeforces.com/problemset/problem/126/B

http://codeforces.com/contest/119/problem/D (7) //[VERY NICE]

https://www.urionlinejudge.com.br/judge/en/problems/view/1348 (4) //[CLASSICAL][NICE][SCC]

11930 UVA (4)

http://codeforces.com/contest/776/problem/D (5)