Graph Algorithms for Coding Interviews: When to Use BFS, DFS, or Dijkstra

Graphs are the most feared topic in coding interviews — not because they're impossible, but because most people learn BFS, DFS, and Dijkstra in isolation without understanding when to use each one. This guide gives you the decision framework that turns graph problems from guesswork into a systematic process. The three algorithms every interviewer expects you to know BFS — Breadth-First Search Data structure: Queue (FIFO) Complexity: O(V + E) time, O(V) space Use when: You need the shortest path