Max Consecutive Ones III
A medium-tier problem at 66% community acceptance, tagged with Array, Binary Search, Sliding Window. Reported in interviews at Sigmoid and 12 others.
Max Consecutive Ones III is a medium-difficulty array problem that looks deceptively simple but punishes naive approaches. You're given a binary array and a flip budget, find the longest subarray of all ones you can create by flipping at most K zeros. LinkedIn, Meta, and Expedia ask this one. The trap is thinking it's a brute-force loop over every window. The pattern that matters is sliding window with a flip counter. If this hits your live OA cold and you blank on the window shrinking logic, StealthCoder surfaces the working solution in seconds, invisible to the proctor.
Companies that ask "Max Consecutive Ones III"
Max Consecutive Ones III is the kind of problem that decides whether you pass. StealthCoder reads the problem on screen and surfaces a working solution in under 2 seconds. Invisible to screen share. The proctor sees nothing. Built by a senior engineer who knows the OA is theater. This is the script.
Get StealthCoderThe trick is sliding window with a constraint tracker, not binary search or prefix sum on their own. You expand the right pointer, count zeros as you go. Once you've used K flips, stop expanding and start shrinking from the left until you're back under K zeros. The window size at any point tells you the longest sequence of ones you can make. Common fail: trying to precompute or overthinking with prefix sums. The actual solution runs one pass left to right, tracking window boundaries. Most candidates who've drilled window problems get this. If you haven't, StealthCoder hedges the live OA by showing exactly how the pointers move and when to shrink.
Pattern tags
You know the problem.
Make sure you actually pass it.
Max Consecutive Ones III recycles across companies for a reason. It's medium-tier, and most candidates blank under the timer. StealthCoder is the hedge: an AI overlay invisible during screen share. It reads the problem and surfaces a working solution in under 2 seconds. Built by a senior engineer who knows the OA is theater. This is the script. Works on HackerRank, CodeSignal, CoderPad, and Karat.
Max Consecutive Ones III interview FAQ
Is this really asked at Meta and LinkedIn?+
Yes. Both companies appear in the top-asker list for this problem. It's popular at mid-tier and senior SDE interviews. You'll see it framed slightly different each time, but the sliding window pattern is the same.
What's the trick I'm missing if I TLE on a brute-force solution?+
You're probably iterating every possible subarray and recounting flips each time. That's O(n^2) or worse. The win is one pass with two pointers and a running flip count. Shrink when over budget. That's O(n) and it's the only real solution.
Does this really need binary search or prefix sum?+
No. Those topics are listed because some solutions sketch them out, but the real pattern is sliding window. Binary search could find the answer if you prefix-sum your zeros first, but it's slower and harder to code under pressure. Stick with the window.
How hard is 65% acceptance rate for a medium?+
That's above average. Most people who drill sliding window patterns will pass. The acceptance rate tells you it's not a rare or trick-heavy problem. If you know the window pattern cold, you're in the top half.
What's the gotcha on edge cases?+
K equals zero (can't flip anything, count consecutive ones as-is), or K is larger than the number of zeros (flip all zeros, answer is array length). Both are easy to miss in a live setting. Walk through your pointer logic with K=0 before submitting.
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