Concepts5

Many competitive programming problems map to a small set of classic patterns; recognizing keywords and constraints lets you pick the right tool fast.

Tree isomorphism asks whether two trees have exactly the same shape, ignoring vertex names.

Dinic's algorithm computes maximum flow by repeatedly building a level graph with BFS and sending a blocking flow using DFS.

Tree diameter is the longest simple path in a tree and can be found with two BFS/DFS runs.

Breadth-First Search (BFS) explores a graph level by level, visiting all vertices at distance d from the source before any at distance d+1.