20\. Valid Parentheses

Easy

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.

**Example 1:**

**Input:** s = "()"

**Output:** true 

**Example 2:**

**Input:** s = "()[]{}"

**Output:** true 

**Example 3:**

**Input:** s = "(]"

**Output:** false 

**Example 4:**

**Input:** s = "([)]"

**Output:** false 

**Example 5:**

**Input:** s = "{[]}"

**Output:** true 

**Constraints:**

*   <code>1 <= s.length <= 10<sup>4</sup></code>
*   `s` consists of parentheses only `'()[]{}'`.