Electrical Efficiency

combinatorics, data structures, dp, math, number theory, trees

Deducing Sortability

binary search, bitmasks, math

Circular Mirror

binary search, combinatorics, geometry, math, two pointers

Basketball Together

binary search, greedy, sortings

Accumulation of Dominoes

math

Even-Odd XOR

bitmasks, constructive algorithms, greedy

L-shapes

dfs and similar, implementation

Counting Rectangles

brute force, data structures, dp, implementation

Line

greedy, sortings

Word Game

data structures, implementation

Colourblindness

implementation

Spell Check

implementation

Matching Reduction

brute force, constructive algorithms, dfs and similar, flows, graph matchings, graphs, interactive

Prefix Function Queries

dfs and similar, dp, hashing, string suffix structures, strings, trees

Maximum AND

bitmasks, dfs and similar, divide and conquer, greedy, sortings

Min-Max Array Transformation

binary search, greedy, two pointers

Deadly Laser

implementation

Image

greedy, implementation

Misha and Paintings

constructive algorithms, data structures, greedy, implementation, math

Xor-Subsequence (hard version)

bitmasks, data structures, dp, strings, trees

Xor-Subsequence (easy version)

bitmasks, brute force, dp, strings, trees, two pointers

Corners

greedy, implementation

Interesting Sum

brute force, data structures, greedy, math, sortings

Burenka Plays with Fractions

math, number theory

Fighting Tournament

binary search, data structures, implementation, two pointers

Mathematical Circus

constructive algorithms, math

Chip Game

games, math

Burenka, an Array and Queries

data structures, math, number theory

Impressionism

constructive algorithms, graphs, implementation, math

Permutation for Burenka

data structures, graph matchings, greedy, math, trees

Tonya and Burenka-179

data structures, greedy, math, number theory

Fibonacci Strings

greedy, implementation, math, number theory

Burenka and Traditions (hard version)

data structures, dp, greedy

Burenka and Traditions (easy version)

dp, greedy

Madoka and The First Session

constructive algorithms, flows, graph matchings, graphs, implementation

Madoka and The Best University

math, number theory

Madoka and The Corruption Scheme

combinatorics, constructive algorithms, greedy, math

Madoka and Formal Statement

greedy

Madoka and Underground Competitions

constructive algorithms, implementation

Madoka and Strange Thoughts

math, number theory

Bags with Balls

combinatorics, dp, math, number theory

Swap and Maximum Block

bitmasks, data structures, dfs and similar, divide and conquer, dp

Chip Move

brute force, dp, math

Robot in a Hallway

data structures, dp, greedy, implementation, ternary search

Permutation Chain

constructive algorithms, math

2-3 Moves

greedy, math

Crop Squares

constructive algorithms, geometry, interactive, math

Long Way Home

data structures, divide and conquer, dp, geometry, graphs, greedy, shortest paths

2+ doors

2-sat, bitmasks, graphs, greedy

Monoblock

combinatorics, data structures, implementation, math

Beautiful Array

constructive algorithms, greedy, math

Crossmarket

constructive algorithms, greedy, math

Path Prefixes

binary search, data structures, dfs and similar, trees

Build a Tree and That Is It

constructive algorithms, implementation, trees

Add Modulo 10

brute force, math, number theory

Color with Occurrences

brute force, data structures, dp, greedy, strings

Minimum Varied Number

greedy

Remove Prefix

data structures, greedy, implementation

Everyone Loves to Sleep

implementation, math

Lost Array

bitmasks, combinatorics, constructive algorithms, dp, math

Cross Swapping

2-sat, data structures, dsu, greedy, matrices

Tournament Countdown

constructive algorithms, greedy, interactive, number theory, probabilities

Build Permutation

constructive algorithms, dp, math

Optimal Reduction

constructive algorithms, sortings

Traveling Salesman Problem

geometry, greedy, implementation

Triameter

binary search, data structures, dfs and similar, trees

LCM Sum (hard version)

brute force, data structures, math, number theory, two pointers

LCM Sum (easy version)

binary search, brute force, combinatorics, math, number theory, two pointers

Empty Graph

binary search, constructive algorithms, data structures, greedy, shortest paths

Sort Zero

greedy, sortings

Woeful Permutation

constructive algorithms, greedy, number theory

Wonderful Permutation

greedy, implementation

Party

brute force, graphs

Perfect Permutation

constructive algorithms

Two Arrays

binary search, games, graph matchings

Recover the Tree

constructive algorithms, trees

XOR Triangle

bitmasks, brute force, constructive algorithms, dp, greedy, math

Rain

binary search, brute force, data structures, geometry, greedy, implementation, math

Color the Picture

constructive algorithms, greedy, math

Multiset of Strings

bitmasks, brute force, dp, fft, flows, graphs, math, meet-in-the-middle, trees

XOR Tree

bitmasks, data structures, dfs and similar, dsu, greedy, trees

Rorororobot

binary search, data structures, greedy, math

Recover an RBS

constructive algorithms, greedy, implementation, strings

Also Try Minecraft

data structures, dp, implementation

Three Doors

brute force, greedy, implementation, math

Difference of GCDs

constructive algorithms, math

Difference Operations

greedy, math

Bugaboo

bitmasks, constructive algorithms, dp, number theory

Replace

binary search, data structures

Partial Virtual Trees

combinatorics, dfs and similar, dp, math, trees

DFS Trees

dfs and similar, dsu, graphs, greedy, sortings, trees

Difference Array

brute force, data structures, implementation, sortings

Doremy's IQ

binary search, constructive algorithms, greedy, implementation

Qpwoeirut and Vertices

binary search, data structures, dfs and similar, divide and conquer, dsu, greedy, trees

Chopping Carrots (Hard Version)

brute force, constructive algorithms, data structures, dp, greedy, math, number theory, two pointers

Chopping Carrots (Easy Version)

binary search, brute force, constructive algorithms, greedy, number theory

Qpwoeirut And The City

dp, flows, greedy, implementation

Making Towers

dp, greedy, math

Another String Minimization Problem

2-sat, constructive algorithms, greedy, string suffix structures, strings

Mark and the Online Exam

bitmasks, constructive algorithms, interactive, probabilities