longestValidParentheses

longestValidParentheses

substring is countinuous.

class Solution:
    def longestValidParentheses(self, s: str) -> int:
        numof_unpaired_left = 0
        numof_illegal_right = 0
        for ele in s:
            if ele == '(':
                numof_unpaired_left += 1
            else: # ele == ')'
                if numof_unpaired_left == 0:
                    numof_illegal_right += 1
                else: 
                # it means numof_unpaired_left > 0
                # numof_unpaired_left never < 0
                    numof_unpaired_left -= 1
        print(numof_unpaired_left)
        print(numof_illegal_right)
        return len(s) - numof_unpaired_left - numof_illegal_right