Moderate Sliding Window Question 93 of 224

How do you find the longest run of 1s in a binary array if you may flip at most k zeros?

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

01234

Index starts at 0. Scan once for max — O(n).

This is a window where the number of zeros is at most k

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
This is a window
where the number of zeros is at most k
2
expand right and shrink
left when zeros exceed k, tracking max length.
3
Time is O(n) and
space is O(1).
4
It is the same
pattern as longest repeating replacement with a two-symbol alphabet.
5
Common mistake
What juniors usually get wrong.
6
Close
When you pick this over the alternative.

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

Say this line

“Time is O(n) and space is O(1).”

Break into beats

TimeisOnandspace

Speaking order

2987408337471632900

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

This is a window where the number of zeros is at most k expand right and shrink left when zeros exceed k, tracking max length.