Graph

Given a sorted dictionary of alien language, find the order of characters in the alien alphabet

Find all possible paths from source node to target node in a directed acyclic graph (DAG)

Find all articulation points in an undirected graph - vertices whose removal increases the number of connected components

Find shortest paths from a source vertex to all other vertices in a weighted graph, capable of handling negative edge weights

Learn BFS shortest path in an unweighted graph: O(V+E) time, queue + parent[] for path reconstruction. Step-by-step for interviews—start now.

Compute shortest distances from a start node in an undirected graph with uniform edge weight using BFS.

Learn BFS traversal with a FIFO queue + visited set. Includes BFS pseudocode, example, and O(V+E) complexity—practice for FAANG interviews.

Find the celebrity in a party of n people using the minimum number of questions.

Create a deep copy of an undirected graph represented with adjacency lists

Determine if you can finish all courses given prerequisite relationships using topological sorting

Determine if a directed graph contains a cycle

Learn graph cycle detection in an undirected graph using DFS/BFS parent tracking or Union-Find (DSU). O(V+E). Step-by-step—practice now.

Find all bridges (critical edges) in an undirected graph using Tarjan's algorithm

Find shortest paths between all pairs of vertices in a weighted graph using dynamic programming

Check if a graph can be colored with exactly two colors such that no two adjacent nodes have the same color

Learn what a minimum spanning tree is + MST algorithm steps. Kruskal (Union-Find) O(E log E) vs Prim (heap) O(E log V). Practice now.

Find the minimum number of swaps required to sort an array.

Find the time it takes for a signal to reach all nodes in a network using shortest path algorithms

Count the number of islands in a 2D grid

Find all strongly connected components in a directed graph

Find a linear ordering of vertices in a directed acyclic graph

Find the shortest transformation sequence from beginWord to endWord using single character changes