Code Room
CodingMediumcod-g209
Subject In place transformsLevel Mid–Senior~25 minCommon in Distributed systems interviewsIndustries Software development

Question

Given an array containing only the integers 0, 1, and 2, sort it in a single pass and with constant extra space so that all 0s come first, then all 1s, then all 2s, and return it. Do not use a counting/two-pass approach; the intended solution makes one linear scan. The array has length >= 1.

Implement
sort_colors(nums: list[int]) → list[int]
Examples
in[[2,0,2,1,1,0]]out[0,0,1,1,2,2]
What a strong answer looks like

State your approach and its time/space complexity out loud before you optimize. Handle the edge cases (empty input, duplicates, overflow), and say why you chose this over the brute force. Green tests are the floor, not the grade.

Vibe coding: describe the solution in plain language (or narrate it) and the coach grades your approach. Generating runnable code from your description is coming next.

Run or narrate your approach, then ask the coach.