Explain BFS and DFS and when to use each, then detect a cycle in a graph.

Graph traversal sits beneath a large family of interview problems. What matters is knowing the BFS-vs-DFS tradeoff (shortest path vs memory shape) and applying it cleanly, then getting the directed-vs-undirected cycle gotcha that trips up most candidates.

Updated Sep 2026 · Grounded in real GenAI, LLM, and AI/ML engineering interview loops and written to a senior-engineer editorial bar.