【Leetcode】【python】Valid Parentheses

题目大意

判断括号开闭

解题思路

栈
简单题，思路正确即可

代码

class Solution(object):    def isValid(self, s):        """        :type s: str        :rtype: bool        """        stack = []        for char in s:            if char == '(' or char == '{' or char == '[':                stack.append(char)                continue            elif char == ')':                temp = '('            elif char == '}':                temp = '{'            elif char == ']':                temp = '['            else:                return False            if stack:                if stack[-1] == temp:                    stack.pop()                else:                    return False            else:                return False        if len(stack) != 0:            return False        return True

由于pop()时会输出pop的数值，所以可以简化：

class Solution:    # @return a boolean    def isValid(self, s):        stack = []        for i in range(len(s)):            if s[i] == '(' or s[i] == '[' or s[i] == '{':                stack.append(s[i])            if s[i] == ')':                if stack == [] or stack.pop() != '(':                    return False            if s[i] == ']':                if stack == [] or stack.pop() != '[':                    return False            if s[i] == '}':                if stack == [] or stack.pop() != '{':                    return False        if stack:            return False        else:            return True

总结