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BFS vs DFS interview

When do you choose BFS vs DFS for graph/tree problems? Give complexity and one example each.

Answers use simple, clear English.

Quick interview answer

BFS (queue): shortest path in unweighted graphs, level-order. DFS (stack/recursion): path existence, topological sort variants, connected components, tree recursion. Both O(V+E).

Detailed answer

BFS (queue): shortest path in unweighted graphs, level-order. DFS (stack/recursion): path existence, topological sort variants, connected components, tree recursion. Both O(V+E). DFS uses O(h) stack; BFS O(width). Prefer iterative DFS/BFS if recursion depth risk.

Real example & use case

BFS: maze fewest steps. DFS: detect cycle in directed graph via colors.

Pros & cons

Pros: right tool clarity. Cons: wrong choice wastes time in interviews.

#dsa#bfs#dfs