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Codeforces Round (Div. 2)
3 days
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Difficulty:
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combinatorics
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
1989E
Distance to Different
combinatorics
,
dp
,
math
2300
x1131
1986G1
Permutation Problem (Simple Version)
binary search
,
brute force
,
combinatorics
,
data structures
,
math
,
number theory
2200
x1009
1985G
D-Function
combinatorics
,
math
,
number theory
1600
x7127
1985E
Secret Box
brute force
,
combinatorics
,
math
1200
x16514
1984H
Tower Capturing
combinatorics
,
dp
,
geometry
3300
x131
1984C2
Magnitude (Hard Version)
combinatorics
,
dp
,
greedy
,
math
1700
x6104
1982E
Number of k-good subarrays
bitmasks
,
brute force
,
combinatorics
,
divide and conquer
,
dp
,
math
,
meet-in-the-middle
2300
x1116
1979C
Earning on Bets
binary search
,
combinatorics
,
constructive algorithms
,
number theory
1200
x16259
1976E
Splittable Permutations
combinatorics
,
data structures
,
dfs and similar
,
greedy
,
math
,
trees
2500
x809
1976D
Invertible Bracket Sequences
binary search
,
combinatorics
,
data structures
,
divide and conquer
,
implementation
,
two pointers
2000
x3449
1975F
Set
bitmasks
,
brute force
,
combinatorics
,
dfs and similar
,
divide and conquer
,
dp
,
math
2600
x676
1974C
Beautiful Triple Pairs
combinatorics
,
data structures
1400
x13932
1967E2
Again Counting Arrays (Hard Version)
combinatorics
,
dp
,
math
3500
x83
1967E1
Again Counting Arrays (Easy Version)
combinatorics
,
dp
,
fft
,
math
3100
x167
1967C
Fenwick Tree
bitmasks
,
brute force
,
combinatorics
,
data structures
,
dp
,
math
,
trees
2300
x1477
1958F
Narrow Paths
*special problem
,
combinatorics
2000
x164
1957E
Carousel of Combinations
brute force
,
combinatorics
,
dp
,
math
,
number theory
2400
x1112
1957C
How Does the Rook Move?
combinatorics
,
dp
,
math
1600
x8610
1954F
Unique Strings
combinatorics
,
dp
,
math
3100
x233
1954D
Colored Balls
combinatorics
,
dp
,
math
,
sortings
1800
x5448
1952E
Sweep Line
combinatorics
,
games
,
math
x221
1951G
Clacking Balls
combinatorics
,
math
,
probabilities
3100
x286
1948F
Rare Coins
combinatorics
,
math
,
probabilities
2500
x1200
1946E
Girl Permutation
combinatorics
,
dp
,
math
,
number theory
2200
x2234
1943D2
Counting Is Fun (Hard Version)
combinatorics
,
dp
2800
x649
1943D1
Counting Is Fun (Easy Version)
brute force
,
combinatorics
,
dp
,
math
2400
x1335
1942G
Bessie and Cards
combinatorics
,
dp
,
math
2800
x408
1942E
Farm Game
combinatorics
,
games
2300
x1545
1935D
Exam in MAC
binary search
,
combinatorics
,
implementation
,
math
1800
x7674
1933G
Turtle Magic: Royal Turtle Shell Pattern
bitmasks
,
brute force
,
combinatorics
,
constructive algorithms
,
dfs and similar
,
math
2300
x911
1931G
One-Dimensional Puzzle
combinatorics
,
math
,
number theory
2000
x2562
1931F
Chat Screenshots
combinatorics
,
dfs and similar
,
graphs
1700
x7346
1931D
Divisible Pairs
combinatorics
,
math
,
number theory
1300
x16971
1930I
Counting Is Fun
combinatorics
3500
x59
1930E
2..3...4.... Wonderful! Wonderful!
combinatorics
,
dp
,
math
2400
x1046
1929F
Sasha and the Wedding Binary Search Tree
brute force
,
combinatorics
,
data structures
,
dfs and similar
,
math
,
trees
2300
x1691
1929D
Sasha and a Walk in the City
combinatorics
,
dp
,
math
,
trees
1900
x4367
1928F
Digital Patterns
combinatorics
,
data structures
,
implementation
,
math
2900
x222
1925D
Good Trip
combinatorics
,
dp
,
math
,
probabilities
1900
x3374
1924E
Paper Cutting Again
combinatorics
,
probabilities
3100
x408
1924D
Balanced Subsequences
combinatorics
,
dp
,
math
2700
x808
1922B
Forming Triangles
combinatorics
,
constructive algorithms
,
math
,
sortings
1200
x19642
1920E
Counting Binary Strings
combinatorics
,
dp
,
math
2100
x2472
1919E
Counting Prefixes
combinatorics
,
constructive algorithms
,
dp
,
implementation
,
math
2600
x802
1917D
Yet Another Inversions Problem
combinatorics
,
data structures
,
dp
,
implementation
,
math
,
number theory
2300
x1700
1917B
Erase First or Second Letter
brute force
,
combinatorics
,
data structures
,
dp
,
strings
1100
x20424
1916H2
Matrix Rank (Hard Version)
combinatorics
,
dp
,
math
,
matrices
,
string suffix structures
2700
x510
1916H1
Matrix Rank (Easy Version)
brute force
,
combinatorics
,
dp
,
math
,
matrices
2700
x591
1914G2
Light Bulbs (Hard Version)
combinatorics
,
data structures
,
dfs and similar
,
dp
,
graphs
,
hashing
2300
x1258
1914G1
Light Bulbs (Easy Version)
brute force
,
combinatorics
,
dfs and similar
,
dp
,
dsu
,
graphs
,
math
,
trees
2100
x1734
1912K
Kim's Quest
bitmasks
,
combinatorics
,
dp
1800
x2176
1912B
Blueprint for Seating
combinatorics
,
divide and conquer
,
math
2100
x961
1910I
Inverse Problem
*special problem
,
combinatorics
,
dp
2700
x46
1909I
Short Permutation Problem
combinatorics
,
dp
,
fft
,
math
1900
x114
1909F2
Small Permutation Problem (Hard Version)
combinatorics
,
dp
,
math
2500
x856
1909F1
Small Permutation Problem (Easy Version)
brute force
,
combinatorics
,
dp
,
math
2200
x1680
1907E
Good Triples
brute force
,
combinatorics
,
number theory
1600
x9366
1906J
Count BFS Graph
combinatorics
,
dp
2100
x687
1906H
Twin Friends
combinatorics
,
dp
2200
x630
1905E
One-X
combinatorics
,
dfs and similar
,
dp
,
math
,
trees
2400
x886
1895F
Fancy Arrays
combinatorics
,
dp
,
math
,
matrices
2600
x661
1893E
Cacti Symphony
combinatorics
,
dfs and similar
,
dp
,
graphs
3500
x184
1886D
Monocarp and the Set
combinatorics
,
data structures
,
math
2100
x3406
1879D
Sum of XOR Functions
bitmasks
,
combinatorics
,
divide and conquer
,
dp
,
math
1700
x6951
1879C
Make it Alternating
combinatorics
,
dp
,
greedy
1300
x15723
1876D
Lexichromatography
combinatorics
,
dfs and similar
,
dsu
,
graphs
,
two pointers
2500
x835
1876B
Effects of Anti Pimples
combinatorics
,
number theory
,
sortings
1500
x7821
1868C
Travel Plan
combinatorics
,
dp
,
implementation
,
math
,
trees
2400
x1107
1866M
Mighty Rock Tower
brute force
,
combinatorics
,
dp
,
math
,
probabilities
2400
x704
1866H
Happy Sets
combinatorics
2100
x1560
1866B
Battling with Numbers
combinatorics
,
math
,
number theory
1400
x7414
1864G
Magic Square
combinatorics
,
constructive algorithms
,
implementation
3100
x255
1863G
Swaps
combinatorics
,
dp
,
graphs
,
math
2800
x587
1862D
Ice Cream Balls
binary search
,
combinatorics
,
constructive algorithms
,
math
1300
x16496
1861E
Non-Intersecting Subpermutations
combinatorics
,
dp
,
implementation
,
math
2300
x1650
1857G
Counting Graphs
combinatorics
,
divide and conquer
,
dsu
,
graphs
,
greedy
,
sortings
,
trees
2000
x4209
1855B
Longest Divisors Interval
brute force
,
combinatorics
,
greedy
,
math
,
number theory
900
x24886
1854C
Expected Destruction
combinatorics
,
dp
,
math
,
probabilities
2500
x1415
1850G
The Morning Star
combinatorics
,
data structures
,
geometry
,
implementation
,
math
,
sortings
1500
x11684
1848F
Vika and Wiki
binary search
,
bitmasks
,
combinatorics
,
divide and conquer
,
dp
,
math
2400
x1488
1847E
Triangle Platinum?
brute force
,
combinatorics
,
implementation
,
interactive
,
math
,
probabilities
2900
x321
1844H
Multiple of Three Cycles
combinatorics
,
data structures
,
dp
,
dsu
,
math
3400
x133
1843D
Apple Tree
combinatorics
,
dfs and similar
,
dp
,
math
,
trees
1200
x17405
1843C
Sum in Binary Tree
bitmasks
,
combinatorics
,
math
,
trees
800
x31887
1842G
Tenzing and Random Operations
combinatorics
,
dp
,
math
,
probabilities
2800
x960
1840C
Ski Resort
combinatorics
,
math
,
two pointers
1000
x25784
1840B
Binary Cafe
bitmasks
,
combinatorics
,
math
1100
x21928
1838E
Count Supersequences
combinatorics
,
dp
,
math
2500
x1395
1837E
Playoff Fixing
combinatorics
,
trees
2200
x2127
1835E
Old Mobile
combinatorics
,
dp
,
probabilities
3500
x218
1833F
Ira and Flamenco
combinatorics
,
constructive algorithms
,
data structures
,
implementation
,
math
,
sortings
,
two pointers
1700
x6966
1832E
Combinatorics Problem
brute force
,
combinatorics
,
dp
2200
x2096
1830C
Hyperregular Bracket Strings
combinatorics
,
greedy
,
hashing
,
math
,
number theory
,
sortings
2400
x1570
1829H
Don't Blame Me
bitmasks
,
combinatorics
,
dp
,
math
1700
x7343
1827A
Counting Orders
combinatorics
,
math
,
sortings
,
two pointers
1100
x18067
1824B2
LuoTianyi and the Floating Islands (Hard Version)
combinatorics
,
dfs and similar
,
math
,
probabilities
,
trees
2300
x2530
1824B1
LuoTianyi and the Floating Islands (Easy Version)
combinatorics
,
math
,
probabilities
,
trees
1800
x4417
1823A
A-characteristic
combinatorics
,
constructive algorithms
,
math
800
x15932
1821F
Timber
combinatorics
,
dp
,
fft
,
math
2600
x723
1821A
Matching
combinatorics
,
math
800
x19550
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