How do you find the longest palindromic substring?
PICTURE THIS: HOW TO EXPLAIN IT
Simple meaning
Expand around each center (and each pair of centers for even length), tracking the longest window.
WHY — Strings instead of guessing?
Why interviewers care about Strings:
question about Strings.
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:
- 1Expand around each center
(and each pair of centers for even length), tracking the longest window.
- 2Time is O(n^2) and
extra space is O(1).
- 3Manacher's algorithm is O(n)
but rarely expected
- 4DP of palindrome booleans
is O(n^2) time and space.
- 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
Expand around each center (and each pair of centers for even length), tracking the longest window. Time is O(n^2) and extra space is O(1).