Stack pattern
Longest Valid Parentheses
Given a string containing only the characters ( and ), return the length of the longest contiguous substring that forms a well-formed (properly matched) sequence of parentheses. Watch it run step by step, then write your own pseudocode and get it checked by AI.
- LeetCode 32
- Hard
- 2 approaches
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StackLeetCode 32
Hard
From the first idea to the best one
- 01 Brute force · balance from every start O(n²)O(1) space
- 02 Optimized · index stack with base O(n)O(n) space
What you will learn
- How to read Longest Valid Parentheses and spot the stack pattern in it
- Brute force · balance from every start: O(n²) time, O(1) space
- Optimized · index stack with base: O(n) time, O(n) space
- The pseudocode for each approach, its line lit as the animation runs
- Practice: write your own pseudocode and get it checked
More Stack
See Longest Valid Parentheses run, step by step
Sign in and this page opens on the animation, with all 8 Stack problems beside it.
DSA comes with the all labs plan and every ChaiCode batch.