How do you compute minutes until all oranges rot using a queue?
PICTURE THIS: STACK VS QUEUE
Simple meaning
Multi-source BFS: enqueue every rotten orange at time 0, then spread to adjacent fresh oranges level by level.
WHY — Queue instead of guessing?
Why interviewers care about Queue:
question about Queue.
trade-offs, and what you would actually do on a DSA project - not buzzwords.
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:
- 1Multi-source BFS: enqueue every
rotten orange at time 0, then spread to adjacent fresh oranges level by level.
- 2Time is O(rows*cols) and
space is O(rows*cols) for the queue.
- 3If any fresh orange
remains when the queue dies, return -1.
- 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
Multi-source BFS: enqueue every rotten orange at time 0, then spread to adjacent fresh oranges level by level. Time is O(rows*cols) and space is O(rows*cols) for the queue.