Count Subarrays of Length Three With a Condition
A easy-tier problem at 62% community acceptance, tagged with Array. Reported in interviews at Cognizant and 0 others.
Count Subarrays of Length Three With a Condition is an easy array problem that shows up in Cognizant assessments. It's exactly the kind of problem that looks trivial until you misread the constraint and waste five minutes debugging. The problem asks you to count subarrays of fixed length three that satisfy a specific mathematical condition. With a 62% acceptance rate, plenty of candidates are getting tripped up on how the condition actually translates to code. If this lands in your live OA and you blank on the pattern, StealthCoder surfaces a working solution in seconds, invisible to the proctor.
Companies that ask "Count Subarrays of Length Three With a Condition"
Count Subarrays of Length Three With a Condition 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. Made for the engineer who has done the work but might still blank with a webcam pointed at him.
Get StealthCoderThe trap here is reading the condition too fast and implementing something that doesn't match. You're iterating through the array once, checking each window of exactly three consecutive elements against a constraint, and incrementing a counter when it passes. The algorithm is O(n) and straightforward, but the condition itself requires careful parsing. Most candidates either misinterpret what 'a condition' means or off-by-one their window boundaries. The actual logic is simple once you read the problem statement twice, but under time pressure during an assessment, that extra read often doesn't happen. This is where StealthCoder acts as your safety net: if you've stalled on understanding the exact constraint, it reads the problem directly from your screen and hands you the correct implementation, letting you move on to harder problems instead of spinning on an easy one.
Pattern tags
You know the problem.
Make sure you actually pass it.
Count Subarrays of Length Three With a Condition recycles across companies for a reason. It's easy-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. Made for the engineer who has done the work but might still blank with a webcam pointed at him. Works on HackerRank, CodeSignal, CoderPad, and Karat.
Count Subarrays of Length Three With a Condition interview FAQ
Is this problem actually easy or just rated easy?+
It's genuinely easy algorithmically: O(n) single pass, no complex data structures. The 62% acceptance rate reflects misreading the condition under pressure, not algorithmic difficulty. Once you parse the constraint correctly, the code writes itself in under two minutes.
Does Cognizant ask other array problems, or is this a one-off?+
The data shows Cognizant has reported this specific problem. Array fundamentals are standard across most assessments, so expect other array work in their OA, but this condition-based counting is their known ask.
What's the common mistake on this problem?+
Misinterpreting the condition statement or implementing a sliding-window approach when a simple linear scan is enough. Some also hardcode loop bounds incorrectly and skip valid subarrays near the end of the array.
Should I use extra space or solve it in-place?+
You don't modify the array, so in-place doesn't apply. You only need a counter variable for the result. No hash maps, no extra arrays needed. Space complexity is O(1) regardless of approach.
How long should this take in a real interview?+
If you read the condition carefully, two to three minutes for a correct solution. If you misread it, you'll spin for ten. The bottleneck is always the first read, not the coding. Double-check the constraint before you type.
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