Given an input string s and a pattern p$,$ implement regular expression matching with support for $\text{'}.\text{'}$ and $\text{'}*\text{'}$ where:

$\text{'}.\text{'}$ Matches any single character.$$

$\text{'}*\text{'}$ Matches zero or more of the preceding element.

The matching should cover the entire input string $($not partial$).$

Example $1$:

Input: s $="$aa$",$ p $="$a$"$

Output: false

Explanation: $"$a$"$ does not match the entire string $"$aa$".$

Example $2$:

Input: s $="$aa$",$ p $="$a$*"$

Output: true

Explanation: $\text{'}*\text{'}$ means zero or more of the preceding element, $\text{'}$a$\text{'}.$ Therefore, by repeating $\text{'}$a$\text{'}$ once, it becomes $"$aa$".$

Example $3$:

Input: s $="$ab$",$ p $=".*"$

Output: true

Explanation: $".*"$ means "zero or more $(*)$ of any character $(.)".$

Constraints:

$1<=$ s$.$length $<=20$

$1<=$ p$.$length $<=20$

s contains only lowercase English letters.

p contains only lowercase English letters, $\text{'}.\text{'},$ and $\text{'}*\text{'}.$

It is guaranteed for each appearance of the character $\text{'}*\text{'},$ there will be a previous valid character to match.