Stairs

combinatorics, divide and conquer, dp, fft, math

XOR and Distance

bitmasks, divide and conquer, trees

Common Divisor Graph

brute force, constructive algorithms, dsu, graphs, hashing, math, number theory

Pairwise Modulo

data structures, math

Permutation Shift

brute force, combinatorics, constructive algorithms, dfs and similar, dsu, graphs, math

Backspace

dp, greedy, strings, two pointers

Penalty

bitmasks, brute force, dp, greedy

Reverse String

brute force, dp, hashing, implementation, strings

Digits Sum

math, number theory

Organizing a Music Festival

dfs and similar, math

Guess the Perimeter

binary search, interactive, number theory

A Serious Referee

bitmasks, brute force, dfs and similar, sortings

Telepanting

binary search, data structures, dp, sortings

Colors and Intervals

constructive algorithms, data structures, greedy, sortings

Array Differentiation

bitmasks, brute force, constructive algorithms, dfs and similar, dp, graphs, math

Maximize the Intersections

combinatorics, constructive algorithms, geometry, greedy, sortings

Running for Gold

combinatorics, graphs, greedy, sortings

Subsequence Permutation

sortings, strings

Equidistant Vertices

brute force, combinatorics, dfs and similar, dp, trees

Fixed Points

binary search, brute force, dp

Domino (hard version)

constructive algorithms, implementation, math

Domino (easy version)

constructive algorithms, math

Interesting Story

greedy, sortings, strings

Wonderful Coloring - 2

binary search, constructive algorithms, data structures, greedy

Wonderful Coloring - 1

greedy, strings

Polycarp and Coins

greedy, math

Jumping Around

binary search, data structures, divide and conquer, dp, dsu, graphs, shortest paths

Stringforces

binary search, bitmasks, brute force, dp, strings, two pointers

Excellent Arrays

binary search, combinatorics, constructive algorithms, implementation, math, sortings, two pointers

Manhattan Subarrays

brute force, geometry, greedy, implementation

Maximum Cost Deletion

greedy, math

Find The Array

greedy, math

Gregor and the Pawn Game

dfs and similar, dp, flows, graph matchings, graphs, greedy, implementation

Gregor and Cryptography

math, number theory

Gregor and the Two Painters

data structures, divide and conquer, graphs, greedy, math

Gregor and the Odd Cows (Hard)

brute force, geometry, math, number theory

Gregor and the Odd Cows (Easy)

bitmasks, geometry, math, number theory

The Three Little Pigs

combinatorics, dp, fft, math

Integers Have Friends

binary search, data structures, divide and conquer, math, number theory, two pointers

Web of Lies

brute force, graphs, greedy

How Many Paths?

dfs and similar, dp, graphs, trees

Array Stabilization (GCD version)

binary search, brute force, data structures, divide and conquer, number theory, two pointers

Air Conditioners

data structures, dp, implementation, shortest paths, sortings, two pointers

Co-growing Sequence

bitmasks, constructive algorithms, greedy

Pair Programming

greedy, two pointers

Alphabetical Strings

greedy, implementation, strings

Shortest Path with Obstacle

implementation, math

AquaMoon and Stolen String

interactive, math

AquaMoon and Two Arrays

brute force, greedy

AquaMoon and Potatoes

brute force, data structures, dp

AquaMoon and Time Stop (hard version)

data structures, dp

AquaMoon and Time Stop (easy version)

data structures, dp

AquaMoon and Wrong Coordinate

constructive algorithms, interactive, math

AquaMoon and Permutations

2-sat, brute force, combinatorics, constructive algorithms, graph matchings, graphs

AquaMoon and Chess

combinatorics, math

AquaMoon and Strange Sort

sortings

The Final Pursuit

bitmasks, constructive algorithms, divide and conquer, graphs, greedy, math

RPD and Rap Sheet (Hard Version)

brute force, constructive algorithms, interactive, math

RPD and Rap Sheet (Easy Version)

bitmasks, constructive algorithms, interactive, math

Need for Pink Slips

bitmasks, brute force, dfs and similar, implementation, math, probabilities

Customising the Track

combinatorics, greedy, math

Exciting Bets

greedy, math, number theory

Abnormal Permutation Pairs (hard version)

combinatorics, dp, fft, math

Abnormal Permutation Pairs (easy version)

combinatorics, dp, fft, math

Priority Queue

combinatorics, dp, implementation, math, ternary search

Strange Function

math, number theory

Plus and Multiply

constructive algorithms, math, number theory

Odd Set

math

Pleasant Pairs

brute force, implementation, math, number theory

Pretty Permutations

constructive algorithms, greedy, implementation

Tasty Dishes

math, matrices

Inverse Inversions

binary search, brute force, data structures

Converging Array (Hard Version)

dp, math

Converging Array (Easy Version)

dp, math

Tree Array

brute force, combinatorics, dp, graphs, math, probabilities, trees

Great Graphs

constructive algorithms, graphs, greedy, shortest paths, sortings

Strange Array

data structures, greedy, sortings

Game with Cards

binary search, constructive algorithms, data structures, dp, greedy, implementation

PriceFixed

binary search, greedy, implementation, sortings, two pointers

Stable Groups

greedy, sortings

Love Song

dp, implementation, strings

Contest Start

combinatorics, geometry, greedy, math

Gift Set

binary search, greedy, math, ternary search

Interesting Function

binary search, dp, math, number theory

Funny Substrings

data structures, hashing, implementation, matrices, strings

Another Problem About Dividing Numbers

constructive algorithms, math, number theory

Number of Pairs

binary search, data structures, math, two pointers

Friends and Candies

greedy, math

Stone Game

brute force, dp, greedy

Figure Fixing

constructive algorithms, dfs and similar, dsu, graphs, greedy, math

Erase and Extend (Hard Version)

binary search, data structures, greedy, hashing, string suffix structures, strings, two pointers

Erase and Extend (Easy Version)

binary search, brute force, dp, greedy, hashing, implementation, string suffix structures, strings, two pointers

Deleting Divisors

games, math, number theory

Challenging Cliffs

constructive algorithms, greedy, implementation, math

Bad Boy

constructive algorithms, greedy, math

Arithmetic Array

greedy, math

Omkar and Akmar

chinese remainder theorem, combinatorics, constructive algorithms, fft, games, geometry, math, meet-in-the-middle, string suffix structures

Omkar and Forest

combinatorics, graphs, math, shortest paths

Omkar and Medians

data structures, greedy, implementation

Diluc and Kaeya

data structures, dp, hashing, number theory