【Leetcode 】括号字符串的最长有效长度

括号字符串的最长有效长度

#
# 
# @param str string字符串 the string
# @return int整型
#
class Solution:
    def maxVaildLength(self , str ):
        # write code here
        dp=[0] * len(str)
        for i in range(1,len(str)):
            if str[i]==")":
                prev= i - dp[i-1]-1
                if prev >= 0 and str[prev]== "(":
                    dp[i]=dp[i-1]+2+(dp[prev-1] if prev >=1 else 0)
        return max(dp)

参考链接：
​​​ https://leetcode-cn.com/problems/longest-valid-parentheses/solution/zui-chang-you-xiao-gua-hao-by-leetcode-solution/​​