[LeetCode] Validate Parentheses

https://leetcode.com/problems/valid-parentheses/ Given a string s containing just the characters '(', ')', '{', '}', '[' and ']', determine if the input string is valid. An input string is valid if: Open brackets must be closed by the same type of brackets.Open brackets must be closed in the correct order. Example 1: Input: s = "()" Output: true Example 2: Input: s = "()[]{}" Output: true Exampl..