Method minAddToMakeValid

String/MinimumAddToMakeParenthesesValid.py:46–66

:type S: str :rtype: int

(self, S)

"""
class Solution(object):
    def minAddToMakeValid(self, S):
        """
        :type S: str
        :rtype: int
        """
        if not S:
            return 0
        t = [S[0]]
        for i in S[1:]:
            if i == ')':
                if not t:
                    t.append(i)
                    continue
                    
                if t[-1] == '(':
                    t.pop()
                else:
                    t.append(i)
            else:
                t.append(i)
        return len(t)