#
# 代码中的类名、方法名、参数名已经指定,请勿修改,直接返回方法规定的值即可
#
# 
# @param s string字符串 
# @return bool布尔型
#
class Solution:
    def isValid(self , s: str) -> bool:
        stack = list()
        for i in s:
            if not stack:
                stack.append(i)
            elif (stack[-1] == '(' and i == ')') or (stack[-1] == '{' and i == '}') or (stack[-1] == '[' and i == ']'):
                stack.pop()
            else:
                stack.append(i)
        
        return len(stack) == 0