Find Target Indices After Sorting Array
A easy-tier problem at 77% community acceptance, tagged with Array, Binary Search, Sorting. Reported in interviews at TikTok and 0 others.
Find Target Indices After Sorting Array sits at the intersection of array manipulation and search, and it's easier than the title suggests. You're given an array and a list of indices, and you need to report what values live at those positions after sorting. TikTok has asked this one. The 77% acceptance rate signals it's a warm-up problem, but the trick is understanding that you don't actually need to sort the array at all. Most candidates overthink it and build the sorted array explicitly, burning time and memory. If this problem hits your live OA and the pattern doesn't click, StealthCoder surfaces the optimal approach in seconds, invisible to the proctor.
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Find Target Indices After Sorting 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. Built by an Amazon engineer who realized the OA tests how well you memorized 200 problems, not how well you code.
Get StealthCoderThe naive path: sort the array, then return the values at the given indices. That works and passes, but it's not optimal. The real insight is that you can sort the indices themselves and directly map each sorted-index value to its position in a sorted array without ever materializing that array. You need to count how many elements are smaller than each target value. This reduces the problem from O(n log n) space down to O(1) extra space if you're clever. Common mistake: candidates build the sorted array first, then loop through target indices. That's correct but wasteful. The trick is to think about the inverse: given a sorted array, what element lands at position k? You can answer that with counting or binary search on a sorted copy. For live assessments, the straightforward sort-then-index approach passes most test suites. But if the evaluator is checking space complexity or you hit a memory constraint, you'll want the counting trick. StealthCoder flags both paths and shows which one your assessment weights.
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Find Target Indices After Sorting 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. Built by an Amazon engineer who realized the OA tests how well you memorized 200 problems, not how well you code. Works on HackerRank, CodeSignal, CoderPad, and Karat.
Find Target Indices After Sorting Array interview FAQ
Is this problem as easy as the 77% acceptance rate suggests?+
Yes. The naive sort-and-index approach is trivial to code and passes all tests. The difficulty rating is accurate. The only catch is recognizing there's a more elegant, space-efficient solution if you think about counting rather than materializing the sorted array.
Does TikTok actually care about the optimal space solution?+
Unknown from the data we have. TikTok asked it, but we don't know their bar or which variant they tested. For safety, know both: the straightforward sort, and the counting-based approach. Most online assessments pass the simple version.
Should I use binary search or sorting for this?+
Sorting is simpler and sufficient for the problem's constraints. Binary search comes up if you're optimizing space and want to count elements smaller than a target without building the sorted array. Sorting alone is the default correct answer.
How does this relate to array and binary search topics?+
Sorting is the obvious array operation. Binary search becomes relevant only if you take the advanced route: sort once, then binary-search on the sorted copy to find where each target index maps. Most candidates never need to go there.
What's the most common pitfall during an interview?+
Off-by-one errors when mapping sorted indices back to original values, or confusing the target indices with their sorted values. Write out a small example by hand first. The problem is deceptively simple, so careless mistakes hurt more.
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