How do you find the intersection of two arrays using a set?
PICTURE THIS: GIT FLOW
Simple meaning
Put the smaller array into a hash set, then walk the other and collect values that exist in the set, optionally using a second set for uniqueness.
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:
- 1Put the smaller array
into a hash set, then walk the other and collect values that exist in the set, optionally using a second set for uniqueness.
- 2Average time is O(n+m)
and space is O(min(n,m)).
- 3Sorting and two-pointer merge
is the no-hash alternative.
- 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
Put the smaller array into a hash set, then walk the other and collect values that exist in the set, optionally using a second set for uniqueness. Average time is O(n+m) and space is O(min(n,m)).