When do you use BFS instead of DFS?
PICTURE THIS: DATA SPLIT
Fit on train, tune on val, report on test once.
Simple meaning
BFS for shortest path in unweighted graphs and level order.
WHY — Graphs instead of guessing?
Why interviewers care about Graphs:
on Graphs.
the situation, the default choice, and one exception - that reads as experience.
Name the idea, why it exists, then one short example.
End with when you use it and one common pitfall.
STEPS — What happens step by step?
Before you speak the answer, walk the interviewer through these steps:
- 1BFS for shortest path
in unweighted graphs and level order.
- 2DFS for connectivity, cycles,
and path existence.
- 3I state the goal
before picking.
- 4Give an example
One tiny concrete case you can say aloud.
- 5Common mistake
What juniors usually get wrong.
- 6Close
When you pick this over the alternative.
EXAMPLE — See it in action
Here's a short line you can speak, broken into clear beats:
Note: Adapt this scaffold to your own project — keep it under 60–90 seconds.
Key takeaway
BFS for shortest path in unweighted graphs and level order. DFS for connectivity, cycles, and path existence.