SureYeaah's blog

By SureYeaah, history, 4 years ago, In English

Hey everyone!

I haven't had much experience with problems that mainly require math(number theory, combinatorics, algebra, etc.) and am looking for a nice collection of such problems.

Thanks in advance :)

 
 
 
 
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4 years ago, # |
  Vote: I like it +16 Vote: I do not like it

Project euler?

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4 years ago, # |
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https://a2oj.com/category?ID=86

it is a collection of math problems on different websites .

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4 years ago, # |
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On recent Insomnia quali. there were 3 math problems."Remember the name" was pure mathematical and too easy."Walter and Sklyer" had some simple combinatorial elements and finding modular inverse,nice medium problem in my opinion."Meth Cooking" also looks like mostly math problem but I came up with false conclusion on contest and after that couldn't make any progress :(

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4 years ago, # |
  Vote: I like it +67 Vote: I do not like it

Good day to you,

well I found a few problems recently, but I can't guarantee that all will be "math you like" — anyway guess it won't harm anyone so here is a list:

Math & Number theory:

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)

Some combinatorics:

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)

Euler:

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

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

Factorisation:

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://www.spoj.com/problems/PUCMMT02/ (7) //wrong bounds- but ll OK

Geometry:

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 //Body 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}

Matrix expo.

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

Some sequences:

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

Prime testing:

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)

Additional:

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

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

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

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

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

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

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

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

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

I'm sorry but it is hard for me to guess what is/isn't math :'(

Anyway this is the list — so feel free to ignore the comments :P

Have nice day,

Good Luck to you!

~/Morass

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    4 years ago, # ^ |
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    * Sploosh *

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    4 years ago, # ^ |
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    The longest comment i have ever seen :)

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    4 years ago, # ^ |
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    I was very surprised that there are no topcoder problems in the very very long comment. Why? Topcoder has many mathematics-like problems.

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      4 years ago, # ^ |
        Vote: I like it +1 Vote: I do not like it

      Well,

      I'm not a clever guy, so I wasn't able to manage to create account + the software (anyhow) on topcoder ... so I didn't solve any problems out there :/

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4 years ago, # |
  Vote: I like it +5 Vote: I do not like it

With round 432 it looks like you are in luck.

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    4 years ago, # ^ |
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    I already gave the IndiaHacks finals, so I can't.