Triangles

combinatorics, graphs, math

Build String

flows, graphs

Nastya and a Game

brute force, implementation, math

Lightsabers (easy)

implementation

Chris and Road

geometry, implementation

Beard Graph

data structures, dsu, trees

Graph Transpositions

dfs and similar, graphs, greedy, shortest paths

Square Root of Permutation

combinatorics, constructive algorithms, dfs and similar, graphs, math

Sockets

greedy, sortings

Hot Days

greedy

Cheap Robot

binary search, dsu, graphs, shortest paths, trees

Pie or die

games

Lizard Era: Beginning

meet-in-the-middle

Presents in Bankopolis

dp, graphs, shortest paths

Invariance of Tree

constructive algorithms, dfs and similar, greedy, trees

Letters Removing

data structures, strings

Natasha, Sasha and the Prefix Sums

combinatorics, dp, math, number theory

Commentator problem

geometry

PermutationForces II

brute force, combinatorics, greedy, sortings, trees, two pointers

Draw Brackets!

*special problem, implementation

Little Pony and Summer Sun Celebration

constructive algorithms, dfs and similar, graphs

EKG

dfs and similar, dp

Palindromic Cut

brute force, implementation, strings

Inversion Expectation

dp, math, probabilities

LaIS

data structures, dp, greedy

Educational Game

greedy

Minimum Array

binary search, brute force, constructive algorithms, data structures, greedy, hashing, two pointers

Serval and Shift-Shift-Shift

bitmasks, brute force, constructive algorithms, implementation

Square-free division (hard version)

data structures, dp, greedy, math, number theory, two pointers

Ant Man

dp, graphs, greedy

Turtles

dp, matrices

Yet Another Segments Subset

data structures, dp, graphs, sortings

Poman Numbers

bitmasks, greedy, math, strings

Daleks' Invasion (easy)

graphs, trees

Tree Destruction

constructive algorithms, dfs and similar, graphs, greedy, trees

Toda 2

greedy, implementation

Bubble Strike

combinatorics, math, probabilities, ternary search

Jamie and Tree

data structures, trees

Educational Game

Treeland Tour

data structures, dfs and similar, dp, trees

Sum

greedy, math

Wires

dfs and similar, graphs, greedy

Ants

brute force, implementation

Bored Bakry

bitmasks, greedy, math, two pointers

The Number of Subpermutations

brute force, data structures, divide and conquer, hashing, math

Intersecting Subtrees

dfs and similar, interactive, trees

Little Girl and Problem on Trees

data structures, graphs, trees

Deleting Numbers

interactive, math, number theory

Very Interesting Game

brute force, number theory

Naughty Stone Piles

greedy

Cactus

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

Username

*special problem, implementation

Circular Mirror

binary search, combinatorics, geometry, math, two pointers

Cubes

games, greedy, implementation

Prefix Enlightenment

dfs and similar, dsu, graphs

Scheme

dfs and similar, graphs, trees

ace5 and Task Order

constructive algorithms, divide and conquer, implementation, interactive, probabilities, sortings

Arthur and Brackets

dp, greedy

Unique Occurrences

data structures, dfs and similar, divide and conquer, dp, dsu, trees

Charming Meals

binary search, brute force, greedy, sortings

Fibonacci Additions

brute force, data structures, hashing, implementation, math

Vladik and Favorite Game

constructive algorithms, dfs and similar, graphs, interactive

Tenzing and Triangle

data structures, dp, geometry, greedy, math

Crypto Lights

combinatorics, dp, math, probabilities

Chain Reaction

binary search, data structures, dsu, greedy, implementation, math, number theory

Animal Observation (easy version)

data structures, dp

Vanya and Treasure

data structures, dp, graphs, shortest paths

AI robots

data structures

On Changing Tree

data structures, graphs, trees

e-Government

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

Hexagonal numbers

*special problem, implementation

Follow Traffic Rules

implementation, math

Second price auction

bitmasks, probabilities

Happy Sets

combinatorics

There Should Be a Lot of Maximums

brute force, data structures, dfs and similar, dp, trees, two pointers

Olya and magical square

constructive algorithms, implementation, math

Restoring Increasing Sequence

binary search, brute force, greedy, implementation

WTF?

*special problem, graph matchings, implementation, trees

Cinema

implementation

Monsters (hard version)

data structures, greedy

Black and White Tree

dfs and similar, greedy, trees

Hyperregular Bracket Strings

combinatorics, greedy, hashing, math, number theory, sortings

Game with Coins

greedy

Tonya and Burenka-179

data structures, greedy, math, number theory

Half Queen Cover

constructive algorithms, math

Changing a String

dp

Modular Sequence

brute force, constructive algorithms, dp, graphs, greedy, math, number theory

Cross Swapping

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

Banquet Preparations 1

greedy

Permutation Sum

bitmasks, combinatorics, dp, implementation, meet-in-the-middle

Partial Sums

combinatorics, math, number theory

Vasya's Function

binary search, implementation, math

Flipping Range

constructive algorithms, dp, greedy, number theory

Session in BSU

binary search, dfs and similar, dsu, graph matchings, graphs

Logging

implementation, strings

Bear and Bowling 4

binary search, data structures, divide and conquer, geometry, ternary search

REQ

data structures, number theory

Noise Level

dfs and similar, implementation, math

Jeff and Permutation

greedy

Drazil Likes Heap

constructive algorithms, data structures, greedy, implementation