Serious Business

data structures, divide and conquer, dp, implementation, shortest paths

Tyler and Strings

combinatorics, data structures, implementation

Integral Array

brute force, constructive algorithms, data structures, math

Madoka and Laziness

dp, greedy

Madoka and the Sixth-graders

data structures, dfs and similar, greedy

Madoka and the Best School in Russia

constructive algorithms, dp, math, number theory

Playing Around the Table

constructive algorithms, greedy, implementation

Power Board

brute force, dp, math, number theory

Weight the Tree

constructive algorithms, dfs and similar, dp, implementation, trees

Basis

combinatorics, fft, math, number theory

Expand the Path

brute force, combinatorics, data structures, implementation, math

Cross Coloring

data structures, implementation, math

Covering Circle

geometry

Special Positions

combinatorics, divide and conquer, fft, math

Two Arrays

bitmasks, brute force, combinatorics, greedy, hashing, math, two pointers

Anonymity Is Important

binary search, brute force, data structures, dsu, greedy, sortings

Repetitions Decoding

constructive algorithms, implementation, sortings

Two Posters

brute force, data structures, greedy, two pointers

Colorful Operations

brute force, data structures, implementation

Big Brush

constructive algorithms, data structures, greedy, implementation

Minimize Inversions Number

data structures, greedy, math, sortings

Birthday

constructive algorithms, greedy, math

Towers

constructive algorithms, dfs and similar, dp, greedy, trees

Best Pair

binary search, brute force, implementation

Yet Another Minimization Problem

dp, greedy, math

Closest Pair

data structures, greedy

Cars

2-sat, constructive algorithms, dfs and similar, dsu, graphs, greedy, sortings

Infinite Set

bitmasks, dp, math, matrices, number theory, strings

Fibonacci Additions

brute force, data structures, hashing, implementation, math

Fair Share

constructive algorithms, data structures, dfs and similar, graph matchings, graphs

Finding Zero

constructive algorithms, interactive, math

Perfect Matching

data structures, divide and conquer, interactive, trees

Spanning Tree Queries

binary search, data structures, dfs and similar, dsu, graphs, greedy, math, sortings, trees

Make Them Equal

dp, greedy

Distance Tree (hard version)

binary search, dfs and similar, shortest paths, trees

Distance Tree (easy version)

binary search, data structures, dfs and similar, graphs, shortest paths, trees

New Year Concert

binary search, data structures, greedy, math, number theory, two pointers

Strange Test

binary search, bitmasks, brute force, dp, math

Making It Bipartite

flows, graph matchings, graphs, number theory

Expected Components

combinatorics, math, number theory, probabilities

Flipping Range

constructive algorithms, dp, greedy, number theory

Paint the Middle

dp, greedy, sortings, two pointers

Range and Partition

binary search, constructive algorithms, data structures, greedy, two pointers

Spaceship Crisis Management

binary search, data structures, geometry, sortings

Groceries in Meteor Town

binary search, data structures, dsu, trees

Game on Sum (Hard Version)

combinatorics, dp, games, math

Game on Sum (Easy Version)

combinatorics, dp, games, math

Grid Xor

constructive algorithms, greedy, implementation, interactive, math

Peculiar Movie Preferences

greedy, strings

Not Splitting

geometry, graphs, greedy, implementation, shortest paths

Not Escaping

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

Not Adding

brute force, dp, math, number theory

A Random Code Problem

combinatorics, dp, math, number theory, probabilities

Black and White Tree

dfs and similar, greedy, trees

Martial Arts Tournament

binary search, brute force, greedy, math

Monsters And Spells

binary search, data structures, dp, greedy, implementation, math, two pointers

Cats on the Upgrade (hard version)

binary search, data structures, dfs and similar, graphs, trees

Cats on the Upgrade (easy version)

brute force, data structures, dfs and similar, divide and conquer, dp, graphs, trees

Binary Spiders

bitmasks, data structures, implementation, math, sortings, trees

Road Optimization

dp

MinOr Tree

bitmasks, dfs and similar, dsu, graphs, greedy

Interacdive Problem

binary search, constructive algorithms, interactive

Masha-forgetful

brute force, constructive algorithms, dp, hashing, implementation, strings

Middle Duplication

data structures, dfs and similar, greedy, strings, trees

Robot Cleaner Revisit

implementation, math, probabilities

Balanced Stone Heaps

binary search, greedy

Quadratic Set

constructive algorithms, hashing, math, number theory

Math Test

bitmasks, brute force, greedy

Shuffle

combinatorics, math, two pointers

Set or Decrease

binary search, brute force, greedy, sortings

Two Sequences

data structures, hashing, string suffix structures

Trains and Airplanes

dfs and similar, graphs, shortest paths, trees

Weighted Increasing Subsequences

data structures, dp, math

Strange Instructions

data structures, greedy, implementation

New School

binary search, data structures, dp, greedy, implementation, sortings

The Winter Hike

constructive algorithms, greedy, math

Hidden Permutations

dfs and similar, interactive, math

Subsequences Galore

bitmasks, combinatorics, dp

Bipartite Array

dp, greedy

Replace the Numbers

constructive algorithms, data structures, dsu, implementation

Exact Change

brute force, constructive algorithms, greedy

BA-String

brute force, dp, greedy, implementation, math

Permutation and Queries

brute force, data structures, divide and conquer, two pointers

Unusual Minesweeper

binary search, dfs and similar, dsu, greedy, sortings

Let's Play the Hat?

brute force, constructive algorithms, greedy, math

MEX and Increments

constructive algorithms, data structures, dp, greedy, implementation, math, sortings

New Year's Problem

binary search, greedy, sortings

Trader Problem

data structures, dsu, greedy, sortings

Reverse

bitmasks, constructive algorithms, dfs and similar, implementation, math, strings

Singers' Tour

constructive algorithms, math

Christmas Chocolates

dfs and similar, dp, games, graphs, implementation, math, number theory, shortest paths, trees

Too Many Impostors (hard version)

constructive algorithms, implementation, interactive, math

Too Many Impostors (easy version)

constructive algorithms, implementation, interactive

Keep XOR Low

bitmasks, combinatorics, data structures, divide and conquer, dp, math

Just Add an Edge

dfs and similar, dp, graphs

Tricolor Triangles

brute force, graphs, math, matrices

Lexicographically Small Enough

brute force, data structures, greedy, strings

Keep the Average High

dp, greedy, math

Reindeer Games

binary search, constructive algorithms, data structures, divide and conquer, flows, graphs, shortest paths

Maximum Adjacent Pairs

constructive algorithms, graph matchings