How do you find whether a sorted array has a pair that sums to a target?
PICTURE THIS: ARRAY IN MEMORY
Index starts at 0. Scan once for max — O(n).
Simple meaning
Place pointers at both ends
WHY — Two Pointers instead of guessing?
Why interviewers care about Two Pointers:
question about Two Pointers.
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:
- 1Define it
Place pointers at both ends
- 2move the left up
if the sum is too small and the right down if it is too large.
- 3The scan is O(n)
after the array is sorted, with O(1) extra space.
- 4If the input is
unsorted, either sort first O(n log n) or use a hash set O(n).
- 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
Place pointers at both ends move the left up if the sum is too small and the right down if it is too large.