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Before contest
Codeforces Round #851 (Div. 2)
2 days
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*has extra registration
→ Filter Problems
Difficulty:
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combine-tags-by-or
*combine tags by OR
2-sat
binary search
bitmasks
brute force
chinese remainder theorem
combinatorics
constructive algorithms
data structures
dfs and similar
divide and conquer
dp
dsu
expression parsing
fft
flows
games
geometry
graph matchings
graphs
greedy
hashing
implementation
interactive
math
matrices
meet-in-the-middle
number theory
probabilities
schedules
shortest paths
sortings
string suffix structures
strings
ternary search
trees
two pointers
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Status
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Custom test
Problems
#
Name
644C
Hostname Aliases
*special problem
,
binary search
,
data structures
,
implementation
,
sortings
,
strings
2100
x878
193B
Xor
brute force
2000
x877
226D
The table
constructive algorithms
,
greedy
2100
x874
220C
Little Elephant and Shifts
data structures
2100
x873
77C
Beavermuncher-0xFF
dfs and similar
,
dp
,
dsu
,
greedy
,
trees
2100
x867
954F
Runner's Problem
dp
,
matrices
,
sortings
2100
x866
31D
Chocolate
dfs and similar
,
implementation
2000
x866
1599H
Hidden Fortress
interactive
,
math
2100
x863
336D
Vasily the Bear and Beautiful Strings
combinatorics
,
math
,
number theory
2100
x861
630P
Area of a Star
geometry
2100
x860
1184A2
Heidi Learns Hashing (Medium)
brute force
,
number theory
2100
x859
18E
Flag 2
dp
2000
x852
171C
A Piece of Cake
*special problem
,
implementation
2000
x845
400E
Inna and Binary Logic
binary search
,
bitmasks
,
data structures
2100
x826
74C
Chessboard Billiard
dfs and similar
,
dsu
,
graphs
,
number theory
2100
x822
958A2
Death Stars (medium)
hashing
,
strings
2000
x808
362D
Fools and Foolproof Roads
data structures
,
dfs and similar
,
dsu
,
graphs
,
greedy
2100
x799
847F
Berland Elections
greedy
,
sortings
2100
x797
457C
Elections
brute force
2100
x792
374D
Inna and Sequence
binary search
,
data structures
,
dp
,
trees
2000
x786
1184E2
Daleks' Invasion (medium)
dfs and similar
,
graphs
,
shortest paths
,
trees
2100
x783
39E
What Has Dirichlet Got to Do with That?
dp
,
games
2000
x783
859D
Third Month Insanity
dp
,
probabilities
,
trees
2100
x778
217B
Blackboard Fibonacci
brute force
,
math
2100
x778
852D
Exploration plan
binary search
,
flows
,
graph matchings
,
shortest paths
2100
x774
245F
Log Stream Analysis
binary search
,
brute force
,
implementation
,
strings
2000
x774
656D
Rosetta Problem
*special problem
2100
x769
119C
Education Reform
dp
2000
x766
720A
Closing ceremony
greedy
2000
x748
1725F
Field Photography
bitmasks
,
data structures
,
sortings
2100
x747
475C
Kamal-ol-molk's Painting
brute force
,
constructive algorithms
,
greedy
2100
x746
253D
Table with Letters - 2
brute force
,
two pointers
2000
x744
82C
General Mobilization
data structures
,
dfs and similar
,
sortings
2000
x743
852E
Casinos and travel
dp
2100
x740
65C
Harry Potter and the Golden Snitch
binary search
,
geometry
2100
x736
26C
Parquet
combinatorics
,
constructive algorithms
,
greedy
,
implementation
2000
x719
13B
Letter A
geometry
,
implementation
2000
x717
784B
Kids' Riddle
*special problem
2000
x716
435D
Special Grid
brute force
,
dp
,
greedy
2000
x716
261C
Maxim and Matrix
constructive algorithms
,
dp
,
math
2000
x715
248C
Robo-Footballer
binary search
,
geometry
2000
x711
225E
Unsolvable
math
,
number theory
2100
x704
542F
Quest
dp
,
greedy
2100
x703
106E
Space Rescuers
geometry
,
ternary search
2100
x702
522C
Chicken or Fish?
greedy
2100
x684
1057C
Tanya and Colored Candies
*special problem
,
dp
2000
x681
784G
BF Calculator
*special problem
2000
x678
50C
Happy Farm 5
geometry
2000
x669
413D
2048
bitmasks
,
dp
2000
x666
656E
Out of Controls
*special problem
2000
x663
126C
E-reader Display
constructive algorithms
,
greedy
2000
x650
182C
Optimal Sum
data structures
,
greedy
2000
x648
58D
Calendar
greedy
,
strings
2000
x637
386C
Diverse Substrings
dp
,
strings
,
two pointers
2000
x634
61C
Capture Valerian
math
2000
x634
195E
Building Forest
data structures
,
dsu
,
graphs
2000
x629
101C
Vectors
implementation
,
math
2000
x629
35E
Parade
data structures
,
sortings
2100
x629
630O
Arrow
geometry
2000
x623
63E
Sweets Game
bitmasks
,
dfs and similar
,
dp
,
games
,
implementation
2000
x615
656C
Without Text
*special problem
2000
x600
66E
Petya and Post
data structures
,
dp
2000
x600
39A
C*++ Calculations
expression parsing
,
greedy
2000
x598
81D
Polycarp's Picture Gallery
constructive algorithms
,
greedy
2100
x586
47C
Crossword
implementation
2000
x584
952E
Cheese Board
2000
x577
109D
Lucky Sorting
constructive algorithms
,
sortings
2000
x577
370D
Broken Monitor
brute force
,
constructive algorithms
,
greedy
,
implementation
2100
x572
132D
Constants in the language of Shakespeare
constructive algorithms
,
dp
,
greedy
2100
x563
50D
Bombing
binary search
,
dp
,
probabilities
2100
x558
1387A
Graph
*special problem
,
binary search
,
dfs and similar
,
dp
,
math
,
ternary search
2100
x555
131F
Present to Mom
binary search
,
two pointers
2000
x546
59D
Team Arrangement
constructive algorithms
,
greedy
,
implementation
2000
x539
267B
Dominoes
dfs and similar
,
graphs
2000
x537
34E
Collisions
brute force
,
implementation
,
math
2000
x530
234H
Merging Two Decks
constructive algorithms
,
greedy
2000
x529
802K
Send the Fool Further! (medium)
dp
,
trees
2100
x528
1219G
Harvester
implementation
2000
x523
69C
Game
implementation
2000
x522
39C
Moon Craters
dp
,
sortings
2100
x522
60C
Mushroom Strife
brute force
,
dfs and similar
2100
x520
163C
Conveyor
sortings
,
two pointers
2100
x517
216E
Martian Luck
math
,
number theory
2000
x514
1218I
The Light Square
2-sat
,
dfs and similar
,
greedy
2100
x511
44J
Triminoes
constructive algorithms
,
greedy
2000
x507
237D
T-decomposition
dfs and similar
,
graphs
,
greedy
,
trees
2000
x500
838B
Diverging Directions
data structures
,
dfs and similar
,
trees
2100
x495
335C
More Reclamation
games
2100
x487
215E
Periodical Numbers
combinatorics
,
dp
,
number theory
2100
x482
45E
Director
constructive algorithms
,
greedy
2000
x481
241C
Mirror Box
geometry
,
implementation
2000
x476
48E
Ivan the Fool VS Gorynych the Dragon
dp
,
games
,
graphs
2100
x469
342D
Xenia and Dominoes
bitmasks
,
dfs and similar
,
dp
2100
x463
73B
Need For Brake
binary search
,
greedy
,
sortings
2000
x462
215C
Crosses
brute force
,
implementation
2100
x455
690D3
The Wall (hard)
dp
2100
x451
132B
Piet
implementation
2100
x443
76B
Mice
greedy
,
two pointers
2100
x443
309A
Morning run
binary search
,
math
,
two pointers
2000
x435
254E
Dormitory
dp
,
implementation
2100
x429
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