20. Valid Parentheses

Given a string containing just the characters '(', ')', '{', '}', '[' and ']', determine if the input string is valid.

An input string is valid if:

1. Open brackets must be closed by the same type of brackets.
2. Open brackets must be closed in the correct order.

Note that an empty string is also considered valid.

Example 1:

Input: "()"
Output: true

Example 2:

Input: "()[]{}"
Output: true

Example 3:

Input: "(]"
Output: false

Example 4:

Input: "([)]"
Output: false

Example 5:

Input: "{[]}"
Output: true

Python

 
class Solution(object):
    def isValid(self, s):
        """
        '(', ')', '{', '}', '[' and ']'
        :type s: str
        :rtype: bool
        """
        temp_list = []
        for i in s:
            if i == "(" or i == "{" or i == "[":
                temp_list.append(i)
            else:
                try:
                    if i == ")" and temp_list[-1] != "(" or i == "}" and temp_list[-1] != "{" or i == "]" and temp_list[-1] != "[":
                        return False
                    temp_list.pop()
                except:
                    return False
        return not temp_list