Weighed Tree Radius

data structures, divide and conquer, implementation, trees

Andrey's Tree

binary search, constructive algorithms, data structures, dfs and similar, dsu, greedy, implementation, trees

Red-Black Cobweb

data structures, divide and conquer, implementation, trees

Twilight and Ancient Scroll (easier version)

dp, hashing, implementation, string suffix structures, strings

Kingdom of Islands

brute force, graphs, implementation

Shrink-Reverse

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

Beautiful Tree

data structures, dfs and similar, graphs, implementation, trees

Polo the Penguin and Lucky Numbers

dp, implementation, math

Hard Design

greedy, implementation, math

Local Deletions

binary search, data structures, implementation

Sasha and a Patient Friend

binary search, data structures, implementation

Hamming Triples

implementation, math, two pointers

Infinite Chess

implementation, shortest paths

Design Tutorial: Learn from a Game

constructive algorithms, implementation

Cute number

binary search, brute force, data structures, dsu, implementation, math

Black Widow

dp, graphs, implementation, math

Playing Around the Table

constructive algorithms, greedy, implementation

Delete The Edges

brute force, constructive algorithms, dfs and similar, graphs, implementation

Triangle Platinum?

brute force, combinatorics, implementation, interactive, math, probabilities

Bear and Chase

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

Tree or not Tree

data structures, divide and conquer, implementation, trees

Johnny and James

greedy, implementation, math, trees

Evaluate RBS

data structures, geometry, implementation, math, sortings

Tape Programming

data structures, implementation

Lucky Pair

combinatorics, data structures, implementation

Karen and Neighborhood

binary search, constructive algorithms, implementation

Digital Patterns

combinatorics, data structures, implementation, math

Two Rooted Trees

data structures, implementation, trees

Deja Vu

constructive algorithms, graphs, implementation

Harry Potter and Moving Staircases

dfs and similar, implementation

Tree Weights

bitmasks, constructive algorithms, data structures, dfs and similar, implementation, math, matrices, number theory, trees

Game of Stacks

brute force, dfs and similar, graphs, implementation, trees

String Distance

binary search, brute force, data structures, hashing, implementation, strings

Xenia and String Problem

dp, hashing, implementation, string suffix structures, strings

Red and Black Tree

dp, implementation, math

Anagram Paths

dp, implementation, trees

Mirror Room

data structures, implementation

Flower-like Pseudotree

constructive algorithms, graphs, greedy, implementation, trees

Sequence Transformation

brute force, data structures, dp, implementation, math

Escaping on Beaveractor

data structures, implementation, trees

Tree and Table

dfs and similar, dp, implementation, trees

Gnomes of Might and Magic

data structures, graphs, implementation, shortest paths

Turtle

dp, implementation

Fibonacci-ish II

data structures, implementation

Get Ready for the Battle

constructive algorithms, implementation

Four Vertices

constructive algorithms, data structures, graphs, greedy, implementation, shortest paths

Perpetual Motion Machine

constructive algorithms, dp, graphs, implementation, math, trees

Magic Square

combinatorics, constructive algorithms, implementation

Harry The Potter

brute force, constructive algorithms, dp, fft, implementation, math

Intranet of Buses

binary search, geometry, implementation, two pointers

Grid Sort

implementation

Cipher

implementation

Digits of Number Pi

dp, implementation, strings

MEX counting

combinatorics, dp, implementation

Qingshan and Daniel

brute force, data structures, greedy, implementation

Air Reform

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

Twilight and Ancient Scroll (harder version)

dp, hashing, implementation, string suffix structures, strings, two pointers

Pepe Racing

constructive algorithms, implementation, interactive, sortings

Strange Permutation

binary search, combinatorics, data structures, dp, graphs, implementation, two pointers

JS Minification

greedy, implementation

Chess Rush

*special problem, combinatorics, dp, implementation, math

Showing Off

flows, graph matchings, greedy, implementation

Multithreading (Hard Version)

combinatorics, implementation, math

Johnny and New Toy

data structures, implementation, math

Swiper, no swiping!

graphs, implementation

Fedya the Potter

binary search, implementation, math, number theory

Passports

dp, implementation

The Fair Nut's getting crazy

data structures, implementation

Flow Control

data structures, dsu, implementation

Maximum Product?

brute force, combinatorics, dp, greedy, implementation, math, two pointers

Red Blue Tree

data structures, implementation, trees

Good Graph

bitmasks, dfs and similar, graph matchings, graphs, implementation

Balance the Cards

constructive algorithms, data structures, divide and conquer, geometry, graphs, implementation

Impressionism

constructive algorithms, graphs, implementation, math

Yin Yang

implementation

Olympiad Training

binary search, data structures, dp, flows, geometry, implementation, sortings

Mainak and the Bleeding Polygon

binary search, geometry, implementation, math

LIS?

data structures, greedy, implementation