- Difficulty: Hard
- Tags: LeetCode, Hard, Stack, String, Dynamic Programming, leetcode-32, O(n), O(1)
Problem
Given a string containing just the characters '(' and ')', return the length of the longest valid (well-formed) parentheses substring.
Example 1:
Input: s = "(()" Output: 2 Explanation: The longest valid parentheses substring is "()".
Example 2:
Input: s = ")()())" Output: 4 Explanation: The longest valid parentheses substring is "()()".
Example 3:
Input: s = "" Output: 0
Constraints:
0 <= s.length <= 3 * 104s[i]is'(', or')'.