Parametric MST

binary search, constructive algorithms, graphs, greedy, math, sortings

Equal Tree Sums

constructive algorithms, dfs and similar, math, trees

Three Minimums

combinatorics, constructive algorithms, divide and conquer, dp, fft, math

Snowy Mountain

data structures, dfs and similar, graphs, greedy, shortest paths, trees

Minimal String Xoration

bitmasks, data structures, divide and conquer, greedy, hashing, sortings, strings

Arithmetic Operations

brute force, data structures, graphs, math

Potion Brewing Class

dfs and similar, math, number theory, trees

Tower Defense

binary search, brute force, data structures

Sum of Matchings

brute force, combinatorics, constructive algorithms, dfs and similar, graph matchings, greedy, math

Counting Shortcuts

data structures, dfs and similar, dp, graphs, shortest paths

Vitaly and Advanced Useless Algorithms

dp, greedy, implementation

Two Avenues

data structures, dfs and similar, graphs

Air Reform

data structures, dfs and similar, divide and conquer, dsu, graphs, implementation, trees

Serious Business

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

Madoka and Laziness

dp, greedy

Madoka and the Sixth-graders

data structures, dfs and similar, greedy

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

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

Closest Pair

data structures, greedy

Cars

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

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

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

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

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

Not Splitting

geometry, graphs, greedy, implementation, shortest paths

Not Escaping

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

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

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

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

Quadratic Set

constructive algorithms, hashing, math, number theory

Math Test

bitmasks, brute force, greedy

Shuffle

combinatorics, math, two pointers

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

Subsequences Galore

bitmasks, combinatorics, dp

Bipartite Array

dp, greedy

Exact Change

brute force, constructive algorithms, greedy

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

Trader Problem

data structures, dsu, greedy, sortings

Reverse

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

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

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

LEGOndary Grandmaster

combinatorics, dp, math

Purple Crayon

data structures, dfs and similar, games, graphs, greedy, math, sortings, trees

X(or)-mas Tree

bitmasks, dfs and similar, dsu, graphs, trees

Divan and a Cottage

binary search, data structures

Divan and Kostomuksha (hard version)

dp, number theory

Divan and Kostomuksha (easy version)

dp, number theory

Tree Coloring

combinatorics, divide and conquer, fft

Crazy Robot

dfs and similar, graphs

Max Sum Array

combinatorics, constructive algorithms, greedy, sortings

Armor and Weapons

brute force, dp, greedy, shortest paths

Messages

brute force, dp, greedy, probabilities, sortings