Leetcode - 20.Valid Parentheses

利用栈

class Solution:
    def isValid(self, s):
        """
        :type s: str
        :rtype: bool
        """
        left = ['(','{','[',]
        right = [')','}',']']

        l = []
        for str in s:
            if str in left:
                l.append(str)
            else:
                if len(l) == 0:
                    return False
                pop = l[len(l)-1]
                if pop in left and left.index(pop) == right.index(str):
                    l.pop()
                else:
                    break
        if l == []:
            return True
        else:
            return False

当dict字典里只有一个元素的时候，查找速度会比list快很多