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Codeforces Round #851 (Div. 2)
37:24:05
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Difficulty:
—
strings
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
1791D
Distinct Split
brute force
,
greedy
,
strings
1000
x15050
1791A
Codeforces Checking
implementation
,
strings
800
x28925
1790A
Polycarp and the Day of Pi
implementation
,
math
,
strings
800
x25231
1781C
Equal Frequencies
brute force
,
constructive algorithms
,
greedy
,
implementation
,
sortings
,
strings
1600
x4994
1779A
Hall of Fame
constructive algorithms
,
greedy
,
strings
800
x20517
1778C
Flexible String
bitmasks
,
brute force
,
strings
x4928
1777F
Comfortably Numb
bitmasks
,
data structures
,
divide and conquer
,
strings
,
trees
x472
1771F
Hossam and Range Minimum Query
binary search
,
bitmasks
,
data structures
,
hashing
,
probabilities
,
strings
,
trees
2500
x584
1771D
Hossam and (sub-)palindromic tree
brute force
,
data structures
,
dfs and similar
,
dp
,
strings
,
trees
2100
x1903
1760B
Atilla's Favorite Problem
greedy
,
implementation
,
strings
800
x29984
1759A
Yes-Yes?
implementation
,
strings
800
x22428
1758A
SSeeeeiinngg DDoouubbllee
constructive algorithms
,
strings
800
x20429
1750F
Majority
combinatorics
,
dp
,
math
,
strings
2700
x479
1750E
Bracket Cost
binary search
,
data structures
,
divide and conquer
,
dp
,
greedy
,
strings
2400
x1090
1748B
Diverse Substrings
brute force
,
implementation
,
strings
1400
x11190
1742F
Smaller
constructive algorithms
,
greedy
,
strings
1500
x7648
1741A
Compare T-Shirt Sizes
implementation
,
implementation
,
strings
800
x24941
1739F
Keyboard Design
bitmasks
,
data structures
,
dp
,
string suffix structures
,
strings
2600
x378
1738H
Palindrome Addicts
data structures
,
strings
3300
x146
1737A
Ela Sorting Books
greedy
,
implementation
,
strings
900
x8860
1736D
Equal Binary Subsequences
constructive algorithms
,
geometry
,
greedy
,
implementation
,
strings
2200
x1992
1735C
Phase Shift
dfs and similar
,
dsu
,
graphs
,
greedy
,
implementation
,
strings
1400
x7884
1730D
Prefixes and Suffixes
constructive algorithms
,
strings
,
two pointers
2200
x2222
1729G
Cut Substrings
combinatorics
,
dp
,
hashing
,
strings
,
two pointers
2100
x1669
1729C
Jumping on Tiles
constructive algorithms
,
strings
1100
x16268
1729B
Decode String
greedy
,
strings
800
x25347
1721E
Prefix Function Queries
dfs and similar
,
dp
,
hashing
,
string suffix structures
,
strings
,
trees
2200
x1448
1720D2
Xor-Subsequence (hard version)
bitmasks
,
data structures
,
dp
,
strings
,
trees
2400
x1422
1720D1
Xor-Subsequence (easy version)
bitmasks
,
brute force
,
dp
,
strings
,
trees
,
two pointers
1800
x4756
1714D
Color with Occurrences
brute force
,
data structures
,
dp
,
greedy
,
strings
1600
x6917
1709C
Recover an RBS
constructive algorithms
,
greedy
,
implementation
,
strings
1800
x7278
1706A
Another String Minimization Problem
2-sat
,
constructive algorithms
,
greedy
,
string suffix structures
,
strings
800
x21011
1704G
Mio and Lucky Array
constructive algorithms
,
fft
,
math
,
strings
3500
x70
1703D
Double Strings
brute force
,
data structures
,
strings
1100
x19220
1703C
Cypher
brute force
,
implementation
,
strings
800
x28348
1703A
YES or YES?
brute force
,
implementation
,
strings
800
x40343
1701E
Text Editor
brute force
,
dp
,
greedy
,
strings
2500
x930
1697C
awoo's Favorite Problem
binary search
,
constructive algorithms
,
data structures
,
greedy
,
implementation
,
strings
,
two pointers
1400
x11819
1691C
Sum of Substrings
brute force
,
constructive algorithms
,
greedy
,
math
,
strings
1400
x12938
1690F
Shifting String
graphs
,
math
,
number theory
,
strings
1700
x5539
1688C
Manipulating History
constructive algorithms
,
greedy
,
strings
1700
x6900
1685B
Linguistics
greedy
,
implementation
,
sortings
,
strings
2000
x2707
1684A
Digit Minimization
constructive algorithms
,
games
,
math
,
strings
800
x21586
1682A
Palindromic Indices
greedy
,
strings
800
x17897
1680C
Binary String
binary search
,
greedy
,
strings
,
two pointers
1600
x7768
1679E
Typical Party in Dorm
bitmasks
,
combinatorics
,
dp
,
strings
2400
x909
1676C
Most Similar Words
brute force
,
greedy
,
implementation
,
implementation
,
math
,
strings
800
x24042
1675E
Replace With the Previous, Minimize
dsu
,
greedy
,
strings
1500
x8177
1674C
Infinite Replacement
combinatorics
,
implementation
,
strings
1000
x19533
1673B
A Perfectly Balanced String?
brute force
,
greedy
,
strings
1100
x12780
1673A
Subtle Substring Subtraction
games
,
greedy
,
strings
800
x17297
1670B
Dorms War
brute force
,
implementation
,
strings
1100
x11245
1669E
2-Letter Strings
data structures
,
math
,
strings
1200
x13343
1663G
Six Characters
*special problem
,
constructive algorithms
,
strings
x161
1663F
In Every Generation...
*special problem
,
strings
x276
1662D
Evolution of Weasels
greedy
,
implementation
,
strings
x1208
1662B
Toys
greedy
,
strings
x113
1660F2
Promising String (hard version)
data structures
,
implementation
,
math
,
strings
2100
x2197
1660F1
Promising String (easy version)
brute force
,
implementation
,
math
,
strings
1700
x6013
1660C
Get an Even String
dp
,
greedy
,
strings
1300
x15847
1659B
Bit Flipping
bitmasks
,
constructive algorithms
,
greedy
,
strings
1300
x9230
1654F
Minimal String Xoration
bitmasks
,
data structures
,
divide and conquer
,
greedy
,
hashing
,
sortings
,
strings
2800
x789
1654B
Prefix Removals
strings
800
x14776
1650A
Deletions of Two Adjacent Letters
implementation
,
strings
800
x30066
1635D
Infinite Set
bitmasks
,
dp
,
math
,
matrices
,
number theory
,
strings
1800
x5065
1634A
Reverse and Concatenate
greedy
,
strings
800
x22377
1628B
Peculiar Movie Preferences
greedy
,
strings
1700
x9720
1626B
Minor Reduction
greedy
,
strings
1100
x19900
1624E
Masha-forgetful
brute force
,
constructive algorithms
,
dp
,
hashing
,
implementation
,
strings
2000
x3334
1624D
Palindromes Coloring
binary search
,
greedy
,
sortings
,
strings
1400
x13478
1623E
Middle Duplication
data structures
,
dfs and similar
,
greedy
,
strings
,
trees
2500
x930
1619A
Square String?
implementation
,
strings
800
x36810
1618F
Reverse
bitmasks
,
constructive algorithms
,
dfs and similar
,
implementation
,
math
,
strings
2000
x3455
1617A
Forbidden Subsequence
constructive algorithms
,
greedy
,
sortings
,
strings
800
x15236
1616E
Lexicographically Small Enough
brute force
,
data structures
,
greedy
,
strings
2200
x2153
1616B
Mirror in the String
greedy
,
strings
1100
x17205
1609B
William the Vigilant
implementation
,
strings
1100
x10767
1608G
Alphabetic Tree
binary search
,
data structures
,
dfs and similar
,
hashing
,
string suffix structures
,
strings
,
trees
3500
x103
1607A
Linear Keyboard
implementation
,
strings
800
x31427
1606A
AB Balance
strings
900
x19235
1605C
Dominant Character
brute force
,
greedy
,
implementation
,
strings
1400
x13584
1598G
The Sum of Good Numbers
hashing
,
math
,
string suffix structures
,
strings
3200
x199
1594C
Make Them Equal
brute force
,
greedy
,
math
,
strings
1200
x14836
1584F
Strange LCS
bitmasks
,
dp
,
graphs
,
greedy
,
strings
2600
x691
1582C
Grandma Capa Knits a Scarf
brute force
,
data structures
,
greedy
,
strings
,
two pointers
1200
x12204
1579A
Casimir's String Solitaire
math
,
strings
800
x32924
1578H
Higher Order Functions
implementation
,
strings
1700
x1760
1575H
Holiday Wall Ornaments
dp
,
strings
2200
x476
1575A
Another Sorting Problem
data structures
,
sortings
,
strings
1100
x3428
1567A
Domino Disaster
implementation
,
strings
800
x26806
1562E
Rescue Niwen!
dp
,
greedy
,
string suffix structures
,
strings
2500
x1179
1560E
Polycarp and String Transformation
binary search
,
implementation
,
sortings
,
strings
1800
x6698
1560D
Make a Power of Two
greedy
,
math
,
strings
1300
x15572
1555D
Say No to Palindromes
brute force
,
constructive algorithms
,
dp
,
strings
1600
x9958
1554D
Diane
constructive algorithms
,
greedy
,
strings
1800
x7794
1553D
Backspace
dp
,
greedy
,
strings
,
two pointers
1500
x11520
1553B
Reverse String
brute force
,
dp
,
hashing
,
implementation
,
strings
1300
x12346
1552A
Subsequence Permutation
sortings
,
strings
800
x21868
1551C
Interesting Story
greedy
,
sortings
,
strings
1500
x11186
1551B1
Wonderful Coloring - 1
greedy
,
strings
800
x26179
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