leetcode-32-最长有效括号

class Solution:
    def longestValidParentheses(self, s: str) -> int:
        n = len(s)
        if n==0:return 0
        dp = [0]*n
        for i in range(len(s)):
            # i-dp[i-1]-1是与当前)对称的位置
            if s[i]==‘)‘ and i-dp[i-1]-1>=0 and s[i-dp[i-1]-1]==‘(‘:
               dp[i]=dp[i-1]+dp[i-dp[i-1]-2]+2
        return max(dp)