Explain Breadth-First Search (BFS). What data structure does it use?

Difficulty: 5/10

graph traversal, queue, shortest path

Breadth-First Search

BFS explores a graph level by level, visiting all vertices at distance one before distance two, and so on. It uses a queue and a visited structure. In an unweighted graph, BFS from a source finds shortest paths in terms of the minimum number of edges.

javascript

1
Primary data structure: Queue.
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Uses visited tracking to avoid repeated processing.
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Finds minimum-edge paths in unweighted graphs.
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Can be used for level-order exploration.

Scenario Questions

0-2 years experience

2-5 years experience

1Our friend‑recommendation feature builds a 2‑hop network using BFS, but the current code is slow. What trade‑offs would you consider to speed it up?

Follow-up Questions