New Year Running

number theory, trees

Rivalries

constructive algorithms, data structures, greedy

Minimal Subset Difference

dp

Omkar and Mosaic

combinatorics, constructive algorithms, math

Military Trainings

Diamond Theft

data structures, greedy

Cursor Distance

Berland Traffic

math, matrices

Mrs. Hudson's Pancakes

brute force, dp

Cursed Game

interactive

AI Takeover

interactive

Row of Models

greedy, sortings

Ordering T-Shirts

greedy

Messages on a Tree

Trains and Airplanes

dfs and similar, graphs, shortest paths, trees

Little Brother

binary search, geometry, sortings

Stock Trading

dp

Deja Vu

constructive algorithms, graphs, implementation

Build Railway Stations

*special problem, greedy, trees

Suns and Rays

constructive algorithms, dfs and similar, implementation

A Convex Game

dsu, games

Distinguish four Pauli gates

TIE fighter

Moonwalk challenge

data structures, strings, trees

The Tournament

Suns and Rays

dfs and similar, implementation

Fibonacci Strings

strings

Array sorting

*special problem, sortings

Multithreading (Hard Version)

combinatorics, implementation, math

Seollal

graphs

Conference Problem

dp

Mini Metro

dp

Evil

math

Hellish Constraints

brute force, dp, two pointers

Doremy's Paint 2

data structures

Bitwise Magic

dp, math

The Doctor Meets Vader (Hard)

flows, shortest paths

Two Sorts

binary search, dfs and similar, math, meet-in-the-middle

Dogecoin

*special problem, *special problem, binary search, data structures

Olympic Games

math

Alice and the Cactus

dfs and similar, graphs, math, probabilities

Tree and Table

dfs and similar, dp, implementation, trees

Code Lock

bitmasks, dp

Strange Triples

brute force, math, number theory

Alesya and Discrete Math

divide and conquer, interactive

Sloth

dfs and similar, dp, graph matchings, trees

Sequence Recovery

bitmasks, data structures, greedy

Gena and Second Distance

geometry

Drawing Circles is Fun

combinatorics, geometry

Tree LGM

constructive algorithms, divide and conquer, games, trees

Minimums or Medians

Game of AI (easy version)

combinatorics, constructive algorithms, dp, fft, math

Escaping on Beaveractor

data structures, implementation, trees

Poachers

dp, games, graphs, trees

Jumping Transformers

dp

Matrix

data structures

Fibonacci Strings

matrices, strings

Dreamoon Loves AA

binary search, greedy

Tennis Rackets

brute force, geometry

Two Characters, Two Colors

binary search, data structures, dp, flows, greedy

Perfectionist Arkadiy

*special problem, number theory

Deleting Substrings

Connected Cubes

constructive algorithms, games

Three Arrays

*special problem, constructive algorithms, implementation, sortings

Epic Convolution

chinese remainder theorem, fft, math, number theory

Arpa’s abnormal DNA and Mehrdad’s deep interest

data structures, string suffix structures

HQ9+

*special problem

Road Problem

graphs

Maximum Sum Subarrays

*special problem, dp

ELCA

data structures, trees

Domain

*special problem, expression parsing

Number Discovery

math

Generate equal superposition of four basis states

Military Trainings

Kotlinforces

*special problem, constructive algorithms, dp

Supercollider

data structures

Guard Duty (hard)

geometry

Inna and Babies

binary search, data structures, dsu, geometry, implementation

Cacti Symphony

combinatorics, dfs and similar, dp, graphs

Dangerous Laser Power

constructive algorithms, dsu, sortings

Distinguish Y, XZ, -Y and -XZ

``Is the number of ones divisible by 3?'' oracle

Help Monks

constructive algorithms

Long sequence

brute force, math, matrices

Min-Fund Prison (Hard)

bitmasks, dfs and similar, dp, graphs, trees

Entangled Substrings

string suffix structures, strings

Growing flowers

data structures

Recover a functional graph

graph matchings

Lift and Throw

brute force

Infinite Chess

implementation, shortest paths

``Is the bit string periodic?'' oracle

Goshtasp, Vishtasp and Eidi

*special problem, greedy, math

Tree and Permutation Game

dfs and similar, games, graphs, trees

The Riddle of the Sphinx

binary search, data structures, data structures, interactive

The Meeting Place Cannot Be Changed

dfs and similar, graphs

Iqea

data structures, dfs and similar, divide and conquer, dsu, shortest paths, trees

Chess Championship

constructive algorithms, flows, greedy, math

The Tournament

brute force

Array Sorting

*special problem

Toys

brute force, combinatorics