1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22class Solution(object): def isValid(self, s): """ :type s: str :rtype: bool """ stack = [] dict_check = {"}": "{", ")": "(", "]": "["} for char in s: if char in dict_check: top = stack.pop() if stack else '#' if top != dict_check[char]: return False else: stack.append(char) return not stack