2020-03-04 Day11 Leetcode: 20. V

class Solution:
    def isValid(self, s: str) -> bool:
        if len(s)==0:
            return True
        out=[]
        for i in s:
            if len(out)==0:
                out.append(i)
            else:
                left=out.pop()
                if (left=="{" and i=="}")or(left=='(' and i==")")or(left=="[" and i=="]"):
                    continue
                else:
                    out.append(left)
                    out.append(i)
        if len(out)==0:
            return True
        else:
            return False