Decryption

constructive algorithms, implementation, math, number theory

Timofey and Black-White Tree

brute force, dfs and similar, divide and conquer, graphs, greedy, math, shortest paths, trees

Omkar and Duck

bitmasks, constructive algorithms, interactive, math

Permutation Shift

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

Recovering BST

brute force, dp, math, number theory, trees

Beautiful Mirrors

data structures, dp, math, probabilities

Monocarp and the Set

combinatorics, data structures, math

Arena

combinatorics, dp, math

Longest Subsequence

brute force, math, number theory

Soldier and Traveling

flows, graphs, math

Height All the Same

combinatorics, constructive algorithms, math, matrices

Watching Fireworks is Fun

data structures, dp, math

Martial Arts Tournament

binary search, brute force, greedy, math

Guess The Maximums

binary search, implementation, interactive, math

Valid Sets

dfs and similar, dp, math, trees

Present

binary search, bitmasks, constructive algorithms, data structures, math, sortings

The Winter Hike

constructive algorithms, greedy, math

Magic Gems

dp, math, matrices

Segment Intersections

brute force, greedy, implementation, math

Gift Set

binary search, greedy, math, ternary search

Restorer Distance

binary search, greedy, math, sortings, ternary search

GCD of an Array

brute force, data structures, hashing, implementation, math, number theory, sortings, two pointers

Round Subset

dp, math

Errich-Tac-Toe (Easy Version)

constructive algorithms, math

Ancient Berland Circus

geometry, math

The Number of Pairs

dp, math, number theory

Maximum Value

binary search, math, sortings, two pointers

Ant colony

data structures, math, number theory

Dune II: Battle For Arrakis

*special problem, data structures, greedy, math

Teams

*special problem, binary search, greedy, math

Morning run

binary search, math, two pointers

Martian Luck

math, number theory

Collisions

brute force, implementation, math

Vectors

implementation, math

Capture Valerian

math

Maxim and Matrix

constructive algorithms, dp, math

Right Expansion Of The Mind

math

Little Elephant and Furik and Rubik

math, probabilities

Idempotent functions

constructive algorithms, graphs, math

Subway Innovation

greedy, math, two pointers

First Digit Law

dp, math, probabilities

Berland University

greedy, math

Intersection

implementation, math

Interesting Game

dp, games, math

Number Busters

binary search, math

Police Patrol

greedy, implementation, math, ternary search

Olya and magical square

constructive algorithms, implementation, math

Circular Mirror

binary search, combinatorics, geometry, math, two pointers

Bubble Strike

combinatorics, math, probabilities, ternary search

Vanya and Field

math

International Olympiad

constructive algorithms, greedy, implementation, math

Jamie and Binary Sequence (changed after round)

bitmasks, greedy, math

Big Maximum Sum

data structures, dp, greedy, implementation, math, trees

Little Elephant and LCM

binary search, combinatorics, dp, math

Pretty Song

math, strings

Geo Game

greedy, interactive, math

Ghosts

geometry, math

A Determined Cleanup

math

Let's Play the Hat?

brute force, constructive algorithms, greedy, math

PLEASE

combinatorics, dp, implementation, math, matrices

Greedy Arkady

math

Vitaly and Cycle

combinatorics, dfs and similar, graphs, math

Multi-Colored Segments

binary search, data structures, math, sortings

Om Nom and Candies

brute force, greedy, math

Maxim and Array

constructive algorithms, data structures, greedy, math

Iahub and Permutations

combinatorics, math

Divisors

interactive, math, number theory

One-Dimensional Puzzle

combinatorics, math, number theory

Pinball

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

Multicolored Markers

binary search, brute force, math, number theory

Petya and Construction Set

constructive algorithms, graphs, math, sortings, trees

Fibonacci-ish

brute force, dp, hashing, implementation, math

Not Quite Lee

combinatorics, dp, math, number theory

Special Permutations

math

Doremy's Pegging Game

combinatorics, dp, math

The Great Equalizer

binary search, data structures, math, sortings

Graph Cost

dp, greedy, math, number theory

Ability To Convert

constructive algorithms, dp, greedy, math, strings

Lynyrd Skynyrd

data structures, dfs and similar, dp, math, trees

Roman Digits

brute force, combinatorics, dp, greedy, math

Fibonacci Strings

greedy, implementation, math, number theory

Intercity Travelling

combinatorics, math, probabilities

MEX vs MED

math, two pointers

Unusual Sequences

bitmasks, combinatorics, dp, math, number theory

No Palindromes

brute force, constructive algorithms, divide and conquer, greedy, hashing, implementation, math, strings

Triangular Paths

constructive algorithms, graphs, math, shortest paths, sortings

Kamil and Making a Stream

math, number theory, trees

Nene and the Mex Operator

bitmasks, brute force, constructive algorithms, divide and conquer, dp, greedy, implementation, math

Counting Arrays

combinatorics, dp, math, number theory

Non-Palindromic Substring

hashing, implementation, math, strings

Let's Play Osu!

dp, math, probabilities

Decreasing Debts

constructive algorithms, data structures, graphs, greedy, implementation, math, two pointers

Ilya And The Tree

dfs and similar, graphs, math, number theory, trees

Cashback

data structures, dp, greedy, math

Cyclic MEX

data structures, implementation, math, two pointers

Salyg1n and Array (simple version)

constructive algorithms, interactive, math

Guess the Permutation

binary search, combinatorics, interactive, math

Pchelyonok and Segments

binary search, data structures, dp, greedy, math

Equation

math

GCD Guess

bitmasks, chinese remainder theorem, constructive algorithms, games, interactive, math, number theory