Two Pointers pattern
Sort Colors
Given an array of objects colored 0, 1, or 2, sort them in place so equal colors are grouped in that order, ideally in a single pass. Watch it run step by step, then write your own pseudocode and get it checked by AI.
- LeetCode 75
- Medium
- 3 approaches
Sign in with Google or GitHub and you land straight on this page. DSA comes with the all labs plan and every ChaiCode batch.
Two PointersLeetCode 75
Medium
From the first idea to the best one
- 01 Brute force · counting sort (two passes) O(n)O(1) space
- 02 Better · two-pass swap partition (in place) O(n)O(1) space
- 03 Optimized · Dutch National Flag (in place, one pass) O(n)O(1) space
What you will learn
- How to read Sort Colors and spot the two pointers pattern in it
- Brute force · counting sort (two passes): O(n) time, O(1) space
- Better · two-pass swap partition (in place): O(n) time, O(1) space
- Optimized · Dutch National Flag (in place, one pass): O(n) time, O(1) space
- The pseudocode for each approach, its line lit as the animation runs
- Practice: write your own pseudocode and get it checked
More Two Pointers
See Sort Colors run, step by step
Sign in and this page opens on the animation, with all 12 Two Pointers problems beside it.
DSA comes with the all labs plan and every ChaiCode batch.