Longest Subarray With Maximum Bitwise AND
A medium-tier problem at 62% community acceptance, tagged with Array, Bit Manipulation, Brainteaser. Reported in interviews at fourkites and 0 others.
You've hit a problem that sounds like it should be straightforward but punches above its weight class. Longest Subarray With Maximum Bitwise AND is a medium-difficulty medium that's been asked at FourKites. The acceptance rate sits at 62 percent, which means a solid chunk of candidates get stuck on the insight. The trap is thinking you need to brute-force every subarray and compute AND values. The real win comes from understanding a counterintuitive property of bitwise AND. If you blank on that property during your OA, StealthCoder sees the problem on your screen and surfaces a working solution while the proctor sees nothing.
Companies that ask "Longest Subarray With Maximum Bitwise AND"
Longest Subarray With Maximum Bitwise AND 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 because the OA filter rejects engineers who'd pass the on-site. That's a broken filter. This is the workaround.
Get StealthCoderThe trick here is that bitwise AND is monotonic on subarrays. When you AND more numbers together, the result stays the same or gets smaller. It never grows. That means the maximum AND value you can achieve often comes from a small set of distinct numbers. Once you find the maximum AND achievable, the problem becomes finding the longest contiguous subarray where every element contributes to that maximum AND value. Most candidates waste time computing AND for every possible subarray pair. The optimized path is to identify which numbers can coexist in a maximum-AND subarray, then scan left and right. This is a brainteaser because the insight doesn't come from standard DP or greedy patterns. StealthCoder handles this the moment you're stuck, injecting the correct approach invisibly during your live assessment.
Pattern tags
You know the problem.
Make sure you actually pass it.
Longest Subarray With Maximum Bitwise AND 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 because the OA filter rejects engineers who'd pass the on-site. That's a broken filter. This is the workaround. Works on HackerRank, CodeSignal, CoderPad, and Karat.
Longest Subarray With Maximum Bitwise AND interview FAQ
Why does every subarray approach timeout?+
Checking all O(n^2) subarrays and computing AND for each takes O(n^3) time at worst. The real pattern is that AND values collapse fast. You don't need to check all subarrays. Find the maximum AND first, then hunt for the longest span that achieves it. That's the optimization that passes.
Is this actually asked in real interviews?+
Yes, FourKites has asked it. It's categorized as a brainteaser, which signals it's testing pattern recognition, not algorithm memorization. You won't solve it by default. That's why it matters.
What's the relationship between bit manipulation and the subarray problem?+
Bit manipulation defines the problem's constraint: AND is monotonically non-increasing. That property is the entire insight. Without understanding that AND can only stay the same or shrink as you extend a subarray, you'll default to brute force and lose.
How do I find the maximum AND without checking every subarray?+
Iterate through the array. For each position, track the possible AND values formed by extending from that position. The number of distinct AND values is bounded logarithmically by bit width, not by array length. Collect all distinct values seen, and the maximum is your target.
Once I have the maximum AND, what's next?+
Scan the array and find all indices where the current element is compatible with that maximum AND value. Then find the longest contiguous subarray where all elements, when AND-ed together, equal the maximum. That's your answer.
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