How do you check whether an array is sorted in non-decreasing order?
PICTURE THIS: ARRAY IN MEMORY
Index starts at 0. Scan once for max — O(n).
Simple meaning
Walk adjacent pairs and return false on the first decrease.
WHY — Arrays instead of guessing?
Why interviewers care about Arrays:
question about Arrays.
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:
- 1Walk adjacent pairs and
return false on the first decrease.
- 2One O(n) pass and
O(1) space is enough.
- 3If the interviewer allows
equals, compare nums[i] <= nums[i+1]
- 4Give an example
strict increase uses <.
- 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
Walk adjacent pairs and return false on the first decrease. One O(n) pass and O(1) space is enough.