🌳 DFS vs BFS : Choose Right in 10 Seconds

👉 DFS (Stack/Recursion): Goes deep first. Great for path existence, cycle detection, or "any valid path".
👉 BFS (Queue): Level by level. Best for shortest path in unweighted graph or "minimum steps".

🗯 Interview Encounter: "Number of islands" or "Shortest path in maze" → BFS wins. "Validate BST" or "Clone graph" → DFS is natural.

✅ Pro Tip: Tell interviewer: “I’ll use BFS for shortest, DFS for space efficiency.” Always mention visited set to avoid cycles. Dry-run small example verbally.