Longest Nice Subarray
A medium-tier problem at 65% community acceptance, tagged with Array, Bit Manipulation, Sliding Window. Reported in interviews at Paytm and 0 others.
Longest Nice Subarray is a medium-difficulty sliding window problem that Paytm uses in their online assessments. You need to find the longest contiguous subarray where every pair of distinct elements has a bitwise AND equal to zero. That constraint sounds straightforward until you hit the sliding window logic in a live OA and realize the state tracking gets tricky fast. The 64% acceptance rate means plenty of candidates get stuck on the two-pointer mechanics or miss the bit manipulation shortcut entirely. If this problem shows up during your assessment and you blank on the approach, StealthCoder surfaces a working solution in seconds, invisible to the proctor.
Companies that ask "Longest Nice Subarray"
Longest Nice Subarray 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 an engineer who got tired of watching his cohort grind for six months and still get filtered at the OA stage.
Get StealthCoderThe trick is recognizing that 'nice' subarrays have a strict bitwise property: no two distinct numbers can share a set bit. That means you can't just expand the window greedily. As you slide right and add new elements, you need to shrink from the left whenever the AND property breaks. The naive approach of checking all pairs in each window fails on time complexity. The real solution uses a sliding window with a set or map to track active bits, and you shrink the window only when necessary. Most candidates either ignore the bit constraint entirely and code a basic subarray length problem, or they overcomplicate the shrinking logic. The pattern ties together Array, Bit Manipulation, and Sliding Window in a way that feels disconnected until it clicks. If you haven't drilled this specific bitwise window pattern, it's exactly the kind of problem where StealthCoder becomes your safety net during a live assessment.
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Longest Nice Subarray 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 an engineer who got tired of watching his cohort grind for six months and still get filtered at the OA stage. Works on HackerRank, CodeSignal, CoderPad, and Karat.
Longest Nice Subarray interview FAQ
What does 'nice subarray' mean in this problem?+
A subarray where every pair of distinct elements has a bitwise AND of zero. In other words, no two different numbers in the subarray can share any set bits. For example, 1 (binary 001) and 2 (binary 010) are nice together because 1 AND 2 equals 0.
Why doesn't a simple nested loop work?+
Checking all pairs in every subarray is O(n^2) or worse. Sliding window reduces it to O(n) because you maintain a valid window and shrink only when the AND property breaks. Without the window optimization, you'll time out on larger inputs.
How do I track which bits are in use?+
Use a set or frequency map of the numbers currently in your window. When you add a new element, check if it shares bits with any existing element. If it does, shrink the window from the left until the violation clears.
Is Longest Nice Subarray still asked after 2024?+
Yes. It's reported from Paytm, and it appears in coding assessments regularly. The bitwise window pattern is fundamental enough that variants keep appearing across companies, even if the exact problem rotates.
How does this relate to other sliding window problems?+
Most sliding window problems shrink when a single condition fails (like sum too large). This one is different: you shrink based on a pairwise property across the entire window. That makes it harder to reason about upfront, which is why runtime preparation with a tool like StealthCoder is valuable if you haven't seen the pattern before.
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