Radix Sort interview questions
3 radix sort problems tagged across recent interview reports. Drilled most heavily by de shaw, doordash, and goldman sachs.
Radix Sort is a non-comparative integer sorting algorithm that processes numbers digit by digit, making it faster than comparison-based sorts for large digit ranges. While only 3 problems across major platforms carry the explicit tag, Radix Sort shows up hard in assessments at De Shaw, DoorDash, and Goldman Sachs, often disguised as a "sort an array" variant with constraints that hint at the pattern. Candidates who recognize when to apply it instead of quicksort or mergesort gain a concrete edge on time complexity.
Most-asked radix sort problems
| # | Problem | Diff | # Companies | Pass % |
|---|---|---|---|---|
| 01 | Sort an Array | MEDIUM | 3 | 57% |
| 02 | Query Kth Smallest Trimmed Number | MEDIUM | 2 | 46% |
| 03 | Maximum Gap | MEDIUM | 1 | 49% |
You can't drill every radix sort variant before the assessment. StealthCoder runs invisibly during screen share and solves whichever variant they throw at you. No browser extension. No detection signature. Built by an Amazon engineer who used it to pass JPMorgan's OA and system design loop.
Get StealthCoderRadix Sort works by bucketing elements at each digit position (units, tens, hundreds, etc.), trading extra space for linear time. The pattern is hardest to spot in problems like Maximum Gap or Query Kth Smallest Trimmed Number, where the constraint on the number of digits or value range makes radix faster than O(n log n). Most candidates default to heapsort or quicksort and hit time limits. StealthCoder recognizes these edge cases instantly: if the integer range is bounded and tight, or if you're sorting by individual digit positions, radix is your answer. Drill the three sample problems in order, start with Sort an Array to build the base case, move to Maximum Gap to see the gap-minimization payoff, then tackle the trimmed number variant for the trickiest input manipulation.
Companies that hire most on radix sort
3 radix sort problems.
You won't drill them all. Pass anyway.
Radix Sort is one of the patterns interviews actually filter on. Memorizing every variant in a week is a fantasy. StealthCoder is the hedge: an AI overlay invisible during screen share. It reads the problem and surfaces a working solution in under 2 seconds, no matter which radix sort flavor lands in your live OA. Built by an Amazon engineer who used it to pass JPMorgan's OA and system design loop. Works on HackerRank, CodeSignal, CoderPad, and Karat.
Radix Sort interview FAQ
When should I use Radix Sort instead of quicksort?+
Radix Sort wins when you're sorting integers with a bounded digit count (small k relative to n) or when the range of values is known and limited. If constraints hint at digit operations or tight time limits on large arrays, radix is often the intended solution. Comparison sorts are O(n log n); radix is O(nk) where k is digit count.
How do I recognize a Radix Sort problem in an OA?+
Look for: large n with tight time limits, integer arrays with bounded ranges, or problems involving digit manipulation (trimmed numbers, specific digit positions). Constraints that say n up to 10^5 or 10^6 paired with value ranges are red flags. Questions asking for sorting without comparison also hint at it.
Which company drills Radix Sort the hardest?+
De Shaw, DoorDash, and Goldman Sachs each have 2 Radix Sort problems in their assessments, tying for the most. TCS, Hive, and Infosys also include it. If you're interviewing at any of these, treat Radix Sort as core material, not optional.
Do I need to memorize the Radix Sort implementation?+
Yes. Unlike recognition-only patterns, you'll code this live. The logic is straightforward, iterate through digit positions, bucket by each digit, then concatenate, but the details matter. Practice the three sample problems until it's muscle memory.
Is Radix Sort tested more than other sorting patterns?+
At the companies listed, yes. De Shaw, DoorDash, and Goldman Sachs weight it heavily. But overall, only 3 tagged problems exist, so it's a specialist pattern. If you see it once in your OA, you're more likely to see it again.