Mirror Box

matrices, trees

M-tree

data structures, math, sortings, trees

Forced Online Queries Problem

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

T-decomposition

dfs and similar, graphs, greedy, trees

Caterpillar

dfs and similar, dp, graphs, trees

Words on Tree

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

Black, White and Grey Tree

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

Babysitting

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

Two-Paths

data structures, dp, trees

Dating

brute force, dfs and similar, graphs, trees

Power Tree

data structures, trees

Game on Tree (Hard)

dfs and similar, dp, games, trees

String Transformation 2

bitmasks, dp, graphs, trees

Unordered Swaps

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

Cow and Vacation

dfs and similar, dsu, trees

Cats on the Upgrade (hard version)

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

Send the Fool Further! (medium)

dp, trees

Cities Excursions

dfs and similar, graphs, trees

Bear and Destroying Subtrees

dp, math, probabilities, trees

Partial Virtual Trees

combinatorics, dfs and similar, dp, math, trees

Clockwork Bomb

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

Maximizing Root

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

Restoring Map

bitmasks, constructive algorithms, trees

Tree-Tac-Toe

constructive algorithms, games, trees

ALT

data structures, flows, graphs, trees

Mex Tree

brute force, dp, trees

Tree Sum

combinatorics, math, trees

MST with Matching

bitmasks, brute force, dsu, graph matchings, trees

Olha and Igor

interactive, probabilities, trees

Maximum Control (medium)

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

Almost All

constructive algorithms, trees

Sandy and Nuts

bitmasks, dp, trees

Pairs of Paths

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

Hyperspace Highways

dfs and similar, graphs, trees

Berland Federalization

dp, trees

James and the Chase

dfs and similar, graphs, probabilities, trees

Lenient Vertex Cover

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

Santa Clauses and a Soccer Championship

constructive algorithms, dfs and similar, graphs, trees

Interstellar battle

math, probabilities, 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

Campus

binary search, data structures, dsu, trees

Ksenia and Pawns

dfs and similar, graphs, implementation, trees

Niyaz and Small Degrees

data structures, dp, trees

XOR Partition

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

Vladislav and a Great Legend

combinatorics, dp, trees

Treeland and Viruses

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

Castle

dp, greedy, probabilities, sortings, trees

XOR and Distance

bitmasks, divide and conquer, trees

Mashmokh and Water Tanks

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

Polo the Penguin and Trees

combinatorics, dfs and similar, trees

Genetic engineering

dp, string suffix structures, trees

Pumping Stations

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

Spiders Evil Plan

greedy, trees

Maze

dfs and similar, dp, probabilities, trees

Colored Subgraphs

dfs and similar, dp, games, greedy, trees

Logistical Questions

dfs and similar, divide and conquer, trees

Diverging Directions

data structures, dfs and similar, trees

Prince's Problem

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

Xors on Segments

data structures, strings, trees

Two Centroids

data structures, dfs and similar, greedy, trees

Roads and Ramen

data structures, trees

Surprise me!

divide and conquer, math, number theory, trees

Sum of Prefix Sums

data structures, divide and conquer, geometry, trees

Dating

greedy, sortings, trees

BinCoin

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

Bracket Insertion

combinatorics, dp, math, trees

Paint Tree

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

DZY Loves Planting

binary search, dsu, trees

Subsequence

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

Yuezheng Ling and Dynamic Tree

data structures, trees

Caterpillar on a Tree

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

Fedor Runs for President

data structures, dp, trees

Chaotic V.

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

Road Projects

dfs and similar, dp, trees

Random Walk

dp, graphs, math, probabilities, trees

XOR, Tree, and Queries

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

Freezing with Style

binary search, data structures, divide and conquer, trees

Preorder Test

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

Village (Maximum)

*special problem, dfs and similar, trees

Autocompletion

*special problem, strings, trees

Nastya and Time Machine

constructive algorithms, dfs and similar, graphs, trees

Complete Mirror

constructive algorithms, dfs and similar, dp, hashing, implementation, trees

Boboniu and Jianghu

dp, greedy, sortings, trees

Singer House

combinatorics, dp, graphs, trees

Thwarting Demonstrations

binary search, data structures, trees

Off by One

constructive algorithms, dfs and similar, geometry, graphs, sortings, trees

Nested Rubber Bands

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

Split

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

Comfortably Numb

bitmasks, data structures, divide and conquer, strings, trees

Tree Queries

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

The Tree Has Fallen!

bitmasks, dfs and similar, math, trees

Game on Tree (Medium)

dfs and similar, dp, games, trees

Groceries in Meteor Town

binary search, data structures, dsu, trees

Good Graph

data structures, dsu, graphs, trees

Christmas Chocolates

dfs and similar, dp, games, graphs, implementation, math, number theory, shortest paths, trees

Algebra Flash

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

Max Mex

data structures, trees

Economic Difficulties

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

Illusions of the Desert

data structures, trees