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Codeforces Round #851 (Div. 2)
2 days
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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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Problems
#
Name
1790F
Timofey and Black-White Tree
brute force
,
dfs and similar
,
divide and conquer
,
graphs
,
greedy
,
math
,
shortest paths
,
trees
2100
x1790
1787E
The Harmonization of XOR
bitmasks
,
constructive algorithms
,
greedy
,
math
2100
x1408
1783D
Different Arrays
brute force
,
dp
,
implementation
2000
x2953
1775E
The Human Equation
greedy
,
implementation
2100
x2191
1772F
Copy of a Copy of a Copy
constructive algorithms
,
dfs and similar
,
graphs
,
implementation
,
sortings
2000
x1468
1771D
Hossam and (sub-)palindromic tree
brute force
,
data structures
,
dfs and similar
,
dp
,
strings
,
trees
2100
x1901
1770D
Koxia and Game
constructive algorithms
,
data structures
,
dfs and similar
,
dsu
,
flows
,
games
,
graph matchings
,
graphs
,
implementation
2000
x2916
1767C
Count Binary Strings
data structures
,
dp
2100
x1838
1764D
Doremy's Pegging Game
combinatorics
,
dp
,
math
2000
x2093
1763C
Another Array Problem
brute force
,
constructive algorithms
,
greedy
2000
x4884
1762D
GCD Queries
constructive algorithms
,
interactive
,
number theory
2100
x2468
1761D
Carry Bit
combinatorics
,
math
2100
x1849
1753C
Wish I Knew How to Sort
dp
,
math
,
probabilities
2000
x2914
1748D
ConstructOR
bitmasks
,
chinese remainder theorem
,
combinatorics
,
constructive algorithms
,
math
,
number theory
2100
x2186
1744F
MEX vs MED
math
,
two pointers
2000
x1987
1741F
Multi-Colored Segments
binary search
,
data structures
,
math
,
sortings
2000
x1686
1734E
Rectangular Congruence
constructive algorithms
,
number theory
2100
x2286
1733D2
Zero-One (Hard Version)
dp
,
greedy
2000
x3249
1732C2
Sheikh (Hard Version)
binary search
,
bitmasks
,
brute force
,
greedy
,
implementation
,
two pointers
2100
x1965
1731E
Graph Cost
dp
,
greedy
,
math
,
number theory
2000
x1976
1729G
Cut Substrings
combinatorics
,
dp
,
hashing
,
strings
,
two pointers
2100
x1667
1726D
Edge Split
brute force
,
constructive algorithms
,
dfs and similar
,
dsu
,
graphs
,
probabilities
,
trees
2000
x2994
1725F
Field Photography
bitmasks
,
data structures
,
sortings
2100
x747
1725C
Circular Mirror
binary search
,
combinatorics
,
geometry
,
math
,
two pointers
2000
x1092
1718B
Fibonacci Strings
greedy
,
implementation
,
math
,
number theory
2000
x2299
1716D
Chip Move
brute force
,
dp
,
math
2000
x4079
1716C
Robot in a Hallway
data structures
,
dp
,
greedy
,
implementation
,
ternary search
2000
x3477
1712D
Empty Graph
binary search
,
constructive algorithms
,
data structures
,
greedy
,
shortest paths
2000
x3657
1710B
Rain
binary search
,
brute force
,
data structures
,
geometry
,
greedy
,
implementation
,
math
2100
x1990
1702G2
Passable Paths (hard version)
data structures
,
dfs and similar
,
trees
2000
x3240
1696E
Placing Jinas
combinatorics
,
math
2000
x3170
1690G
Count the Trains
binary search
,
data structures
,
greedy
,
sortings
2000
x2587
1685B
Linguistics
greedy
,
implementation
,
sortings
,
strings
2000
x2704
1684E
MEX vs DIFF
binary search
,
brute force
,
constructive algorithms
,
data structures
,
greedy
,
two pointers
2100
x2618
1682D
Circular Spanning Tree
constructive algorithms
,
implementation
,
trees
2000
x2719
1680E
Moving Chips
bitmasks
,
dp
,
greedy
2000
x3079
1674G
Remove Directed Edges
dfs and similar
,
dp
,
graphs
2000
x1948
1674E
Breaking the Wall
binary search
,
brute force
,
constructive algorithms
,
greedy
,
math
2000
x5130
1672F1
Array Shuffling
constructive algorithms
,
graphs
,
greedy
2000
x2558
1671E
Preorder
combinatorics
,
divide and conquer
,
dp
,
dsu
,
hashing
,
sortings
,
trees
2100
x2269
1667B
Optimal Partition
data structures
,
dp
2100
x2904
1666J
Job Lookup
constructive algorithms
,
dp
,
shortest paths
,
trees
2100
x1096
1665D
GCD Guess
bitmasks
,
chinese remainder theorem
,
constructive algorithms
,
games
,
interactive
,
math
,
number theory
2000
x3042
1660F2
Promising String (hard version)
data structures
,
implementation
,
math
,
strings
2100
x2197
1657D
For Gamers. By Gamers.
binary search
,
brute force
,
greedy
,
math
,
sortings
2000
x4202
1654D
Potion Brewing Class
dfs and similar
,
math
,
number theory
,
trees
2100
x2478
1650G
Counting Shortcuts
data structures
,
dfs and similar
,
dp
,
graphs
,
shortest paths
2100
x1971
1646D
Weight the Tree
constructive algorithms
,
dfs and similar
,
dp
,
implementation
,
trees
2000
x2894
1641B
Repetitions Decoding
constructive algorithms
,
implementation
,
sortings
2000
x3379
1638D
Big Brush
constructive algorithms
,
data structures
,
greedy
,
implementation
2000
x3607
1637E
Best Pair
binary search
,
brute force
,
implementation
2100
x2788
1634D
Finding Zero
constructive algorithms
,
interactive
,
math
2000
x3786
1632D
New Year Concert
binary search
,
data structures
,
greedy
,
math
,
number theory
,
two pointers
2000
x3798
1628D1
Game on Sum (Easy Version)
combinatorics
,
dp
,
games
,
math
2100
x2408
1626D
Martial Arts Tournament
binary search
,
brute force
,
greedy
,
math
2100
x3295
1624F
Interacdive Problem
binary search
,
constructive algorithms
,
interactive
2000
x2728
1624E
Masha-forgetful
brute force
,
constructive algorithms
,
dp
,
hashing
,
implementation
,
strings
2000
x3334
1622D
Shuffle
combinatorics
,
math
,
two pointers
2000
x3242
1621D
The Winter Hike
constructive algorithms
,
greedy
,
math
2100
x3609
1620D
Exact Change
brute force
,
constructive algorithms
,
greedy
2000
x3406
1619G
Unusual Minesweeper
binary search
,
dfs and similar
,
dsu
,
greedy
,
sortings
2000
x1858
1619F
Let's Play the Hat?
brute force
,
constructive algorithms
,
greedy
,
math
2000
x1753
1618F
Reverse
bitmasks
,
constructive algorithms
,
dfs and similar
,
implementation
,
math
,
strings
2000
x3455
1616D
Keep the Average High
dp
,
greedy
,
math
2000
x4057
1614D1
Divan and Kostomuksha (easy version)
dp
,
number theory
2100
x3079
1613E
Crazy Robot
dfs and similar
,
graphs
2000
x4310
1612E
Messages
brute force
,
dp
,
greedy
,
probabilities
,
sortings
2000
x2035
1610D
Not Quite Lee
combinatorics
,
dp
,
math
,
number theory
2000
x2288
1606E
Arena
combinatorics
,
dp
,
math
2100
x2767
1605D
Treelabeling
bitmasks
,
constructive algorithms
,
dfs and similar
,
games
,
greedy
,
implementation
,
trees
2100
x2484
1599H
Hidden Fortress
interactive
,
math
2100
x863
1599C
Bubble Strike
combinatorics
,
math
,
probabilities
,
ternary search
2000
x1288
1598E
Staircases
brute force
,
combinatorics
,
data structures
,
dfs and similar
,
dp
,
implementation
,
math
2100
x1961
1593F
Red-Black Number
dfs and similar
,
dp
,
implementation
,
math
,
meet-in-the-middle
2100
x1995
1584D
Guess the Permutation
binary search
,
combinatorics
,
interactive
,
math
2000
x3121
1582E
Pchelyonok and Segments
binary search
,
data structures
,
dp
,
greedy
,
math
2000
x3069
1575L
Longest Array Deconstruction
data structures
,
divide and conquer
,
dp
,
sortings
2100
x920
1574D
The Strongest Build
binary search
,
brute force
,
data structures
,
dfs and similar
,
graphs
,
greedy
,
hashing
,
implementation
2000
x3892
1571F
Kotlinforces
*special problem
,
constructive algorithms
,
dp
2000
x142
1567D
Expression Evaluation Error
constructive algorithms
,
greedy
,
implementation
,
math
2000
x4050
1566E
Buds Re-hanging
constructive algorithms
,
dfs and similar
,
dp
,
greedy
,
trees
2000
x3654
1560F2
Nearest Beautiful Number (hard version)
bitmasks
,
brute force
,
constructive algorithms
,
dfs and similar
,
dp
,
greedy
2100
x3605
1558C
Bottom-Tier Reversals
constructive algorithms
,
greedy
2000
x2784
1555E
Boring Segments
data structures
,
sortings
,
trees
,
two pointers
2100
x3314
1553E
Permutation Shift
brute force
,
combinatorics
,
constructive algorithms
,
dfs and similar
,
dsu
,
graphs
,
math
2100
x2937
1551E
Fixed Points
binary search
,
brute force
,
dp
2000
x3146
1551D2
Domino (hard version)
constructive algorithms
,
implementation
,
math
2100
x2370
1547G
How Many Paths?
dfs and similar
,
dp
,
graphs
,
trees
2100
x2381
1538G
Gift Set
binary search
,
greedy
,
math
,
ternary search
2100
x3850
1538E
Funny Substrings
data structures
,
hashing
,
implementation
,
matrices
,
strings
2100
x2484
1536D
Omkar and Medians
data structures
,
greedy
,
implementation
2000
x4175
1530E
Minimax
constructive algorithms
,
greedy
,
strings
2100
x2638
1525E
Assimilation IV
combinatorics
,
dp
,
math
,
probabilities
,
two pointers
2100
x1639
1525C
Robot Collisions
data structures
,
greedy
,
implementation
,
sortings
2000
x3850
1521C
Nastia and a Hidden Permutation
constructive algorithms
,
interactive
2000
x3967
1516D
Cut
binary search
,
data structures
,
dp
,
graphs
,
number theory
,
two pointers
2100
x3358
1514D
Cut and Stick
binary search
,
data structures
,
greedy
,
implementation
,
sortings
2000
x3628
1513D
GCD and MST
constructive algorithms
,
dsu
,
graphs
,
greedy
,
number theory
,
sortings
2000
x4113
1511E
Colorings and Dominoes
combinatorics
,
dp
,
greedy
,
math
2100
x2185
1510G
Guide
2100
x1151
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