Two Pointers pattern
Valid Triangle Number
Given an array of non-negative integers representing side lengths, count how many triplets can form a valid triangle. Watch it run step by step, then write your own pseudocode and get it checked by AI.
- LeetCode 611
- Medium
- 2 approaches
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Two PointersLeetCode 611
Medium
From the first idea to the best one
- 01 Brute force O(n³)O(1) space
- 02 Optimized · fix k + two pointers O(n²)O(1) space
What you will learn
- How to read Valid Triangle Number and spot the two pointers pattern in it
- Brute force: O(n³) time, O(1) space
- Optimized · fix k + 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 Valid Triangle Number 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.