Squares of a Sorted Array
A easy-tier problem at 73% community acceptance, tagged with Array, Two Pointers, Sorting. Reported in interviews at Ozon and 12 others.
Squares of a Sorted Array shows up in screens from Uber, Meta, Instacart, and CrowdStrike, and it's deceptively easy to botch. You get an array that's sorted but contains negatives. Square them all and return sorted. Most candidates see 'sorted array' and jump to the obvious O(n log n) sort, burning time and missing the real trick. The pattern is clean once you see it, but if you're tired or blank on two pointers during the live assessment, StealthCoder surfaces the linear solution in seconds, invisible to the proctor.
Companies that ask "Squares of a Sorted Array"
Squares of a Sorted Array 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 by an Amazon engineer who watched the leaked-problem repo become an industry secret. He decided you should have it too.
Get StealthCoderThe trap is assuming the squared values stay sorted when the input is negative-heavy. A negative far from zero squares larger than a small positive. The real approach: two pointers, one at each end. The largest squares live at both extremes. Build the output array backwards, comparing and placing the bigger square at the current tail. It's O(n) time, O(1) extra space if you ignore the output. Most failures come from trying to be clever with sorting instead of recognizing the two-pointer geometry. This is a pointer-manipulation warmup that preps you for harder array problems. If the pattern doesn't click before your OA, StealthCoder runs silently during the assessment and gives you the working solution so you can move on and tackle harder problems.
Pattern tags
You know the problem.
Make sure you actually pass it.
Squares of a Sorted Array 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 by an Amazon engineer who watched the leaked-problem repo become an industry secret. He decided you should have it too. Works on HackerRank, CodeSignal, CoderPad, and Karat.
Squares of a Sorted Array interview FAQ
Why doesn't sorting work here?+
Sorting works but costs O(n log n). The input is already sorted, so you're wasting time and operations. Two pointers exploits the sorted property and runs in linear time. Interviewers at Meta and Uber want you to see that waste and optimize.
Is this still asked at FAANG companies?+
Yes. Meta, Uber, Instacart, CrowdStrike, and Walmart Labs all report it. It's a common warm-up or easy slot in technical phone screens. The acceptance rate is high (73%), so it's not a filter problem, but you still need to nail the two-pointer approach.
How does two pointers apply to harder problems?+
Two pointers teaches you to exploit sorted structure and build output by comparing extremes. That pattern scales to container-with-most-water, merge sorted arrays, and substring problems. Master it here and it's muscle memory for medium questions.
What's the most common mistake?+
Forgetting that negatives squared are large. Candidates sort or iterate left-to-right and miss that the biggest squares are at both ends. The second trap is building the output wrong order, leading to off-by-one bugs.
Can I solve this without extra space?+
Not really if you need the output sorted. You can do it in-place with a two-pass approach, but the standard answer uses a result array and fills it backwards. O(n) time, O(n) space for output. That's the acceptable trade-off.
Want the actual problem statement? View "Squares of a Sorted Array" on LeetCode →