题解 | 有效括号序列

#
# 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:
        # write code here
        stack = []
        for c in s:
            if c == ")":#小括号匹配
                if len(stack) > 0 and stack[-1] == "(":
                    stack.pop()
                else:
                    return False
            elif c == "]":#中括号匹配
                if len(stack) > 0 and stack[-1] == "[":
                    stack.pop()
                else:
                    return False
            elif c == "}":#大括号匹配
                if len(stack) > 0 and stack[-1] == "{":
                    stack.pop()
                else:
                    return False
            else:#正括号入栈
                stack += c
        return True if len(stack)==0 else False#判断是否完全匹配完