Split

binary search, data structures, divide and conquer, dsu, math, trees, two pointers

Nested Rubber Bands

constructive algorithms, dfs and similar, dp, math, trees

Singer House

combinatorics, dp, graphs, trees

Preorder Test

binary search, dfs and similar, dp, graphs, greedy, trees

Village (Maximum)

*special problem, dfs and similar, trees

Freezing with Style

binary search, data structures, divide and conquer, trees

XOR, Tree, and Queries

bitmasks, constructive algorithms, dfs and similar, dsu, graphs, greedy, implementation, trees

Road Projects

dfs and similar, dp, trees

Chaotic V.

dp, graphs, greedy, math, number theory, trees

Random Walk

dp, graphs, math, probabilities, trees

Caterpillar on a Tree

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

Yuezheng Ling and Dynamic Tree

data structures, trees

Subsequence

brute force, divide and conquer, dp, greedy, trees

Fedor Runs for President

data structures, dp, trees

DZY Loves Planting

binary search, dsu, trees

Paint Tree

constructive algorithms, divide and conquer, geometry, sortings, trees

Bracket Insertion

combinatorics, dp, math, trees

BinCoin

binary search, divide and conquer, hashing, implementation, probabilities, trees

Sum of Prefix Sums

data structures, divide and conquer, geometry, trees

Surprise me!

divide and conquer, math, number theory, trees

Roads and Ramen

data structures, trees

Xors on Segments

data structures, strings, trees

Prince's Problem

brute force, data structures, math, number theory, trees

Two Centroids

data structures, dfs and similar, greedy, trees

Diverging Directions

data structures, dfs and similar, trees

Logistical Questions

dfs and similar, divide and conquer, trees

Maze

dfs and similar, dp, probabilities, trees

Spiders Evil Plan

greedy, trees

Colored Subgraphs

dfs and similar, dp, games, greedy, trees

Dating

greedy, sortings, trees

Genetic engineering

dp, string suffix structures, trees

Mashmokh and Water Tanks

binary search, data structures, greedy, trees, two pointers

Polo the Penguin and Trees

combinatorics, dfs and similar, trees

Castle

dp, greedy, probabilities, sortings, trees

Pumping Stations

brute force, dfs and similar, divide and conquer, flows, graphs, greedy, trees

XOR and Distance

bitmasks, divide and conquer, trees

Vladislav and a Great Legend

combinatorics, dp, trees

Ksenia and Pawns

dfs and similar, graphs, implementation, trees

Niyaz and Small Degrees

data structures, dp, trees

Campus

binary search, data structures, dsu, trees

Edge Elimination

constructive algorithms, dfs and similar, dp, trees

Tree Weights

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

Santa Clauses and a Soccer Championship

constructive algorithms, dfs and similar, graphs, trees

Interstellar battle

math, probabilities, trees

Lenient Vertex Cover

dfs and similar, divide and conquer, dsu, graphs, trees

XOR Partition

binary search, bitmasks, data structures, divide and conquer, greedy, trees

James and the Chase

dfs and similar, graphs, probabilities, trees

Berland Federalization

dp, trees

Pairs of Paths

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

Hyperspace Highways

dfs and similar, graphs, trees

Treeland and Viruses

data structures, dfs and similar, dp, shortest paths, trees

Sandy and Nuts

bitmasks, dp, trees

Almost All

constructive algorithms, trees

Maximum Control (medium)

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

Olha and Igor

interactive, probabilities, trees

Restoring Map

bitmasks, constructive algorithms, trees

Tree Sum

combinatorics, math, trees

ALT

data structures, flows, graphs, trees

Maximizing Root

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

Mex Tree

brute force, dp, trees

Clockwork Bomb

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

Bear and Destroying Subtrees

dp, math, probabilities, trees

Partial Virtual Trees

combinatorics, dfs and similar, dp, math, trees

Cities Excursions

dfs and similar, graphs, trees

Send the Fool Further! (medium)

dp, trees

Cats on the Upgrade (hard version)

binary search, data structures, dfs and similar, graphs, trees

Tree-Tac-Toe

constructive algorithms, games, trees

Cow and Vacation

dfs and similar, dsu, trees

MST with Matching

bitmasks, brute force, dsu, graph matchings, trees

Unordered Swaps

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

String Transformation 2

bitmasks, dp, graphs, trees

Dating

brute force, dfs and similar, graphs, trees

Power Tree

data structures, trees

Black, White and Grey Tree

binary search, constructive algorithms, dfs and similar, dp, greedy, trees

Two-Paths

data structures, dp, trees

Babysitting

2-sat, binary search, data structures, graphs, trees

Caterpillar

dfs and similar, dp, graphs, trees

Words on Tree

2-sat, dfs and similar, dsu, graphs, trees

T-decomposition

dfs and similar, graphs, greedy, trees

Forced Online Queries Problem

data structures, divide and conquer, dsu, graphs, trees

M-tree

data structures, math, sortings, trees

Mirror Box

matrices, trees

Multiset of Strings

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

Petya and Tree

binary search, dfs and similar, probabilities, sortings, trees

Michael and Hotel

binary search, interactive, trees

Random Function and Tree

combinatorics, dp, trees

Choosing Two Paths

dfs and similar, dp, greedy, trees

Timofey and a flat tree

data structures, graphs, hashing, shortest paths, trees

Birthday

data structures, dfs and similar, dp, trees

Tree Queries

brute force, dp, trees

Game of Stacks

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

Mashtali and Hagh Trees

combinatorics, dp, trees

Cleaning Robots

dp, trees

Tree Cutting (Hard Version)

combinatorics, dfs and similar, dp, trees

Daleks' Invasion (hard)

data structures, dsu, graphs, trees

Ehab and a weird weight formula

data structures, trees

Jamie and To-do List

data structures, interactive, trees

Balance

constructive algorithms, dfs and similar, graphs, trees

Tree Elimination

dp, trees

Dasha and cyclic table

bitmasks, brute force, fft, strings, trees