20. Valid Parentheses

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.
3. Every close bracket has a corresponding open bracket of the same type.

 

Example 1:

Input: s = "()"
Output: true

Example 2:

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

Example 3:

Input: s = "(]"
Output: false

 

Constraints:

• 1 <= s.length <= 104
• s consists of parentheses only '()[]{}'.

---

class Solution:
    def isValid(self, s: str) -> bool:
        max=int(len(s)/2);       
        if len(s)%2==1:
            return False
        for i in range(max):
            s=s.replace("[]","")
            s=s.replace("()","")
            s=s.replace("{}","")
        if s=="":
            return True
        return False