How do you rearrange a string so the same characters are at least distance k apart?
PICTURE THIS: STACK VS QUEUE
Simple meaning
Greedy with a max-heap of frequencies and a cooldown queue of length k-1.
WHY — Heap instead of guessing?
Why interviewers care about Heap:
question about Heap.
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:
- 1Greedy with a max-heap
of frequencies and a cooldown queue of length k-1.
- 2Always place the currently
most frequent eligible character.
- 3Time is O(n log
A) and space is O(A).
- 4If placement fails before
the string is filled, it is impossible.
- 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
Greedy with a max-heap of frequencies and a cooldown queue of length k-1. Always place the currently most frequent eligible character.