class Solution:
    def longestValidParentheses(self, s: str) -> int:
        n = len(s)
        dp = [0] * n
        best = 0
        for i in range(1, n):
            if s[i] == ")":
                if s[i - 1] == "(":
                    dp[i] = (dp[i - 2] if i >= 2 else 0) + 2
                elif i - dp[i - 1] - 1 >= 0 and s[i - dp[i - 1] - 1] == "(":
                    dp[i] = dp[i - 1] + 2
                    if i - dp[i - 1] - 2 >= 0:
                        dp[i] += dp[i - dp[i - 1] - 2]
                best = max(best, dp[i])
        return best