Query Kth Smallest Trimmed Number
A medium-tier problem at 46% community acceptance, tagged with Array, String, Divide and Conquer. Reported in interviews at DE Shaw and 1 others.
Query Kth Smallest Trimmed Number is a medium-difficulty problem that shows up in OAs from DE Shaw and Goldman Sachs. The acceptance rate sits at 45%, which means half the candidates who attempt it don't land a clean solution. You're given an array of numeric strings and need to find the kth smallest number after trimming each string to a specific digit range. The trick isn't the sorting itself, it's recognizing which algorithmic approach scales without blowing your memory or time budget. If this problem hits your live assessment and you freeze on the pattern, StealthCoder surfaces a working solution in seconds, invisible to the proctor.
Companies that ask "Query Kth Smallest Trimmed Number"
Query Kth Smallest Trimmed Number 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 StealthCoderMost candidates reach for full sorting on the entire array, which works but wastes effort on strings you don't need to compare. The real pattern: for each query, you're only hunting the kth smallest of a trimmed subset, not sorting the whole thing. The trick is understanding when to use Quickselect (average O(n) time) versus Radix Sort (linear time on digit comparisons), and when a Heap or even brute-force sorting is actually the cleaner move given the constraints. The problem also tests your comfort with string slicing and comparing numeric strings lexicographically without converting to integers. Common failure: comparing strings as strings instead of recognizing that leading zeros matter. This is where the Divide and Conquer framing and Array manipulation intersect. StealthCoder is your hedge if you blank on whether Quickselect or Radix Sort is the fastest path, or if you mishandle the string trimming logic under time pressure.
Pattern tags
You know the problem.
Make sure you actually pass it.
Query Kth Smallest Trimmed Number 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. 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.
Query Kth Smallest Trimmed Number interview FAQ
Why is the acceptance rate only 45%?+
Most candidates implement a naive sort for each query, which passes but is inefficient. Others mishandle the string trimming logic or mix up lexicographic and numeric comparison. The problem rewards algorithmic choice, not just correctness. De Shaw and Goldman Sachs ask it partly to see if you pick the right tool.
Is Quickselect or Radix Sort better for this?+
Quickselect is O(n) average and cleaner to code. Radix Sort is O(n * k) where k is digit count, guaranteed linear. For most contest constraints, Quickselect is safer and faster. Radix Sort shines only if n is huge and k is tiny. Both beat full sorting.
Do I really need Divide and Conquer here?+
Not strictly. Divide and Conquer helps if you're partitioning the string array by trimmed range to parallelize or isolate subproblems. Most passing solutions just apply Quickselect or Radix Sort directly on the trimmed strings for each query. It's listed as a topic but not mandatory.
What's the gotcha with string comparison?+
Numeric strings compare lexicographically, not by value. '9' > '10' as strings. The problem asks you to trim each string and then compare them as numbers. Some candidates forget the trim step or compare untrimmed strings, which kills correctness.
Is this still asked at DE Shaw and Goldman Sachs?+
Yes, it's reported from both firms. The exact frequency is unclear, but it's in their active rotation. Both value efficient algorithm selection, so this problem fits their bar. Expect similar string and selection challenges in their OAs.
Want the actual problem statement? View "Query Kth Smallest Trimmed Number" on LeetCode →