Two Pointers pattern
3Sum
Given an integer array, find all unique triplets that sum to zero, with no duplicate triplets in the result. Watch it run step by step, then write your own pseudocode and get it checked by AI.
- LeetCode 15
- Medium
- 2 approaches
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Two PointersLeetCode 15
Medium
From the first idea to the best one
- 01 Brute force O(n³)O(n) space
- 02 Optimized · sort + two pointers O(n²)O(1) space
What you will learn
- How to read 3Sum and spot the two pointers pattern in it
- Brute force: O(n³) time, O(n) space
- Optimized · sort + two pointers: O(n²) 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 3Sum 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.