Triangles

combinatorics, graphs, math

Daleks' Invasion (easy)

graphs, trees

Orientation of Edges

dfs and similar, graphs

Bug in Code

data structures, graphs, implementation, two pointers

Dependency management

*special problem, graphs, implementation

Jzzhu and Cities

graphs, greedy, shortest paths

Directing Edges

constructive algorithms, dfs and similar, graphs

Reachability from the Capital

dfs and similar, graphs, greedy

Captain Flint and Treasure

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

Bertown roads

dfs and similar, graphs

Monopole Magnets

constructive algorithms, dfs and similar, dsu, graphs

Number of Simple Paths

combinatorics, dfs and similar, graphs, trees

Buy a Ticket

data structures, graphs, shortest paths

GCD and MST

constructive algorithms, dsu, graphs, greedy, number theory, sortings

Crazy Robot

dfs and similar, graphs

The Door Problem

2-sat, dfs and similar, dsu, graphs

Subsequences (easy version)

dp, graphs, implementation, shortest paths

Paths and Trees

graphs, greedy, shortest paths

AB Graph

brute force, constructive algorithms, graphs, greedy, implementation

Cheap Dinner

brute force, data structures, graphs, greedy, implementation, sortings, two pointers

The Strongest Build

binary search, brute force, data structures, dfs and similar, graphs, greedy, hashing, implementation

Orac and Game of Life

dfs and similar, graphs, implementation, shortest paths

Counting Graphs

combinatorics, divide and conquer, dsu, graphs, greedy, sortings, trees

Garland

dfs and similar, graphs, greedy, trees

Time to Run

constructive algorithms, graphs, implementation

Koxia and Game

constructive algorithms, data structures, dfs and similar, dsu, flows, games, graph matchings, graphs, implementation

Edge Split

brute force, constructive algorithms, dfs and similar, dsu, graphs, probabilities, trees

Ilya And The Tree

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

Decreasing Debts

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

Matching vs Independent Set

constructive algorithms, graphs, greedy, sortings

Mahmoud and a Dictionary

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

Nash Matrix

constructive algorithms, dfs and similar, graphs, implementation

Count Paths

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

Gourmet choice

dfs and similar, dp, dsu, graphs, greedy

Shortest Path

graphs, shortest paths

Triangular Paths

constructive algorithms, graphs, math, shortest paths, sortings

Array Shuffling

constructive algorithms, graphs, greedy

Rudolf and Subway

constructive algorithms, dfs and similar, graphs, shortest paths

Vlad and the Mountains

binary search, data structures, dsu, graphs, implementation, sortings, trees, two pointers

Sum Graph

brute force, constructive algorithms, graphs, implementation, interactive, shortest paths, trees

Dima and Bacteria

dsu, graphs, shortest paths

Cycle

dfs and similar, graphs

Petya and Construction Set

constructive algorithms, graphs, math, sortings, trees

Jeremy Bearimy

dfs and similar, graphs, greedy, trees

Remove Directed Edges

dfs and similar, dp, graphs

Mars rover

dfs and similar, graphs, implementation, trees

Work Group

dfs and similar, dp, graphs, strings, trees

Copy of a Copy of a Copy

constructive algorithms, dfs and similar, graphs, implementation, sortings

Vitaly and Cycle

combinatorics, dfs and similar, graphs, math

Infinite Maze

dfs and similar, graphs

Roma and Poker

dp, graphs

World Tour

graphs, shortest paths

Olympiad in Programming and Sports

dp, flows, graphs, greedy

Elongated Matrix

binary search, bitmasks, brute force, dp, graphs

Dasha and Puzzle

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

Theseus and labyrinth

graphs, implementation, shortest paths

Polycarp and Hay

dfs and similar, dsu, graphs, greedy, sortings

Restoration of string

constructive algorithms, graphs, implementation

Gifts by the List

constructive algorithms, dfs and similar, graphs, trees

Sereja and the Arrangement of Numbers

graphs, greedy, sortings

Build String

flows, graphs

Wires

dfs and similar, graphs, greedy

Hydra

graphs, sortings

Knights

geometry, graphs, shortest paths, sortings

Idempotent functions

constructive algorithms, graphs, math

Building Forest

data structures, dsu, graphs

Dominoes

dfs and similar, graphs

T-decomposition

dfs and similar, graphs, greedy, trees

Minimum spanning tree for each edge

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

Connected Components?

data structures, dfs and similar, dsu, graphs

Water Tree

data structures, dfs and similar, graphs, trees

Police Stations

constructive algorithms, dfs and similar, dp, graphs, shortest paths, trees

Coloring Edges

constructive algorithms, dfs and similar, graphs

Weights Distributing

brute force, graphs, greedy, shortest paths, sortings

Moving to the Capital

dfs and similar, dp, graphs, shortest paths

Reducing Delivery Cost

brute force, graphs, shortest paths

Cut

binary search, data structures, dp, graphs, number theory, two pointers

Ehab's Last Corollary

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

Olya and Energy Drinks

data structures, dfs and similar, graphs, shortest paths

We Need More Bosses

dfs and similar, graphs, trees

Destroying Roads

constructive algorithms, graphs, shortest paths

Segment Tree

data structures, dsu, graphs, trees

Challenges in school №41

brute force, constructive algorithms, games, graphs, greedy, implementation, sortings

Soldier and Traveling

flows, graphs, math

Permutation Shift

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

Timofey and Black-White Tree

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

Graph Coloring

dfs and similar, dp, graphs

Sleepy Game

dfs and similar, dp, games, graphs

Monsters

brute force, data structures, dfs and similar, dsu, graphs, greedy

How Many Paths?

dfs and similar, dp, graphs, trees

Euclid's nightmare

bitmasks, dfs and similar, dsu, graphs, greedy, math, sortings

Tree with Small Distances

dp, graphs, greedy

Pathwalks

data structures, dp, graphs

Clique Partition

brute force, constructive algorithms, graphs, greedy, implementation

Speedrun

brute force, dfs and similar, dp, graphs, greedy, math, sortings, two pointers

Breaking Good

dfs and similar, dp, graphs, shortest paths

MST Unification

binary search, dsu, graphs, greedy

Tree Constructing

constructive algorithms, graphs

Counting Shortcuts

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

Unstable String Sort

data structures, dfs and similar, dsu, graphs, greedy, implementation, strings