[Leetcode] Easy : Valid Parentheses

Description

Given a string s 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.

 

My solution

class Solution:
    def isValid(self, s: str) -> bool:
        stack = []
        for i in s:
            if i in ('(', '[', '{'):
                stack.append(i)
            elif len(stack) == 0 and i in (')', ']', '}'):
                stack.append(i)
                break
            elif i == ')' and stack[-1] == '(':
                stack.pop()
            elif i == ']' and stack[-1] == '[':
                stack.pop()
            elif i == '}' and stack[-1] == '{':
                stack.pop()
            else:
                break
        return True if len(stack) == 0 else False