How do you merge overlapping intervals?
PICTURE THIS: GIT FLOW
Simple meaning
Sort intervals by start time, then scan and either extend the last merged interval when the next start is at most the current end, or push a new interval.
WHY — Arrays instead of guessing?
Why interviewers care about Arrays:
question about Arrays.
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:
- 1Sort intervals by start
time, then scan and either extend the last merged interval when the next start is at most the current end, or push a new interval.
- 2Sorting is O(n log
n) and the merge scan is O(n), with O(n) space for the output.
- 3Forgetting to sort is
the usual bug.
- 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
Sort intervals by start time, then scan and either extend the last merged interval when the next start is at most the current end, or push a new interval. Sorting is O(n log n) and the merge scan is O(n), with O(n) space for the output.