High Sliding Window Question 151 of 224

How do you find the maximum in every sliding window of size k?

DSA interview set · Speak this in 60–90 seconds · Faridabad & Delhi NCR

Without indexScan every row

With indexJump to keys

CostWrites slower

Maintain a deque of indices with values in decreasing order

Why interviewers care about Sliding Window:

This is a process

question about Sliding Window.

Panels listen for order,

trade-offs, and what you would actually do on a DSA project - not buzzwords.

Stay structured

Name the idea, why it exists, then one short example.

Close cleanly

End with when you use it and one common pitfall.

Before you speak the answer, walk the interviewer through these steps:

1
Maintain a deque of
indices with values in decreasing order
2
the front is the
window max.
3
Pop back while the
new value is larger, pop front when it leaves the window.
4
Each index enters and
leaves once: O(n) time and O(k) space.
5
A heap of (value,
index) is O(n log n) with lazy deletes.
6
Close
When you pick this over the alternative.

Here's a short line you can speak, broken into clear beats:

Say this line

“Each index enters and leaves once: O(n) time and O(k) space.”

Break into beats

Eachindexentersandleavesonce

Speaking order

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Note: Adapt this scaffold to your own project — keep it under 60–90 seconds.

Maintain a deque of indices with values in decreasing order the front is the window max.