How do you find the majority element that appears more than n/2 times?
PICTURE THIS: HASH MAP
Simple meaning
Boyer-Moore voting keeps a candidate and a count, resetting when the count hits zero
WHY — Hashing instead of guessing?
Why interviewers care about Hashing:
question about Hashing.
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:
- 1Boyer-Moore voting keeps a
candidate and a count, resetting when the count hits zero
- 2Why it exists
the guaranteed majority wins.
- 3That is O(n) time
and O(1) space.
- 4A hash map of
frequencies is O(n) space and easier to explain if you have not memorized voting.
- 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
Boyer-Moore voting keeps a candidate and a count, resetting when the count hits zero the guaranteed majority wins.