It's basically max consecutive ones with flips, just dressed up in a server theme.
Use a sliding window technique to maintain a window with at most k zeros, expanding the right pointer and shrinking the left when zeros exceed k. Track the maximum window length seen. This yields an O(n) time, O(1) space solution.
Pro tip: Clarify that the problem is equivalent to finding the longest subarray with at most k zeros, and mention that the window never needs to shrink below the current maximum length, which simplifies the code.
Restate the problem: find the longest contiguous subarray that can be made all 1s by flipping at most k zeros. Confirm with the interviewer that flipping means changing 0 to 1.
Recognize this as a sliding window problem because we need the longest subarray satisfying a constraint (at most k zeros). Explain why brute force is inefficient.
Initialize left and right pointers, a zero count, and max length. Expand right, increment zero count if element is 0. While zero count > k, move left and decrement zero count if element is 0. Update max length.
State that each element is visited at most twice, so time complexity is O(n) and space complexity is O(1).
Walk through a small example, e.g., [1,0,1,0,1], k=1, to verify the algorithm returns 3. Also consider edge cases like all zeros or k >= number of zeros.
AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.