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.

Constraints:

• 0 <= s.length <= 10^4
• s consists of parentheses only '()[]{}'

Example 1: Input: s = "()" Output: true

Example 2: Input: s = "()[]{}" Output: true

Example 3: Input: s = "(]" Output: false

Source: Apple Onsite