32. Longest Valid Parentheses
String
Dynamic Programming
Stack
Given a string containing just the characters '(' and ')', return the length of the longest valid (well-formed) parentheses substring.
Examples
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 ')'.