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32. Longest Valid Parentheses
Hard
Given a string containing just the characters '(' and ')', find 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')'.
Solution
function longestValidParentheses(s: string): number {
let open = 0
let close = 0
let max = 0
for (let char of s) {
if (char === '(') {
open++
} else {
close++
}
if (open === close) {
max = Math.max(max, open + close)
} else if (close > open) {
open = 0
close = 0
}
}
open = 0
close = 0
for (let i = s.length - 1; i >= 0; i--) {
if (s[i] === '(') {
open++
} else {
close++
}
if (open === close) {
max = Math.max(max, open + close)
} else if (open > close) {
open = 0
close = 0
}
}
return max
}
export { longestValidParentheses }