Sort Colors
A medium-tier problem at 68% community acceptance, tagged with Array, Two Pointers, Sorting. Reported in interviews at Pocket Gems and 32 others.
Sort Colors is a medium-difficulty array problem that shows up in live assessments at Microsoft, TikTok, Walmart Labs, Target, and 29 other companies. It looks deceptively simple: you've got an array of 0s, 1s, and 2s that need to be sorted in place. The trap is that most candidates reach for a built-in sort or a counting approach, and while those work, they miss the two-pointer technique the interviewer is actually fishing for. If this problem hits your live OA and you blank on the in-place trick, StealthCoder surfaces a working solution invisibly, in seconds.
Companies that ask "Sort Colors"
Sort Colors 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 problem forces you to sort without extra space and without calling a library sort. The real trick is the Dutch national flag partition: three pointers (left, right, middle) that move through the array in one pass, swapping elements until all 0s are on the left, all 2s on the right, and all 1s in the middle. Most candidates either try a two-pass counting approach or fumble the pointer logic on the first attempt. The two-pointer pattern here is the exact technique that reappears in harder partitioning problems. If you freeze during the live assessment, StealthCoder runs invisibly and gives you the pointer-based solution so you can execute and move on.
Pattern tags
You know the problem.
Make sure you actually pass it.
Sort Colors 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. 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.
Sort Colors interview FAQ
Is Sort Colors still asked at big tech companies?+
Yes. It appears across 33 companies in recent reports, including Microsoft, TikTok, and Walmart Labs. It's not trendy or hard enough to skip, so treat it as a realistic problem that could appear in your OA tomorrow.
What's the trick everyone misses?+
The Dutch national flag pattern. Instead of counting or using extra space, you use three pointers in one pass to partition the array in place. The left pointer expands the 0 zone, the right shrinks the 2 zone, and the middle pointer explores. Most candidates don't see this on the first try.
Can I just sort it with a built-in function?+
It'll work and pass, but the interviewer is testing whether you know the two-pointer partitioning pattern, not whether you can call sort(). If you want to ace the follow-up, understand the three-pointer approach instead.
How does this relate to other array problems?+
Sort Colors teaches the partition pattern used in quicksort and in problems like Kth Largest Element and Partition Array. Once you nail the pointer logic here, you'll recognize the pattern in harder problems and solve them faster.
How long should this take in a live assessment?+
If you know the two-pointer trick, 10 to 15 minutes from problem read to working code. If you don't, you'll spend 30+ minutes debugging a counting or sorting approach. That's why having a safety net like StealthCoder matters on live OAs.
Want the actual problem statement? View "Sort Colors" on LeetCode →