Given an input string `s` and a pattern `p`, implement regular expression matching with support for `'.'` and `'*'` where:
- `'.'` Matches any single character.
- `'*'` 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:"*" means zero or more of the preceding element, "a". Therefore, by repeating "a" 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, '.', and '*'.
- It is guaranteed for each appearance of the character '*', there will be a previous valid character to match.