A phrase is a palindrome if it reads the same from left to right and from right to left, after two clean-up steps. First, change every capital letter to a small letter. Second, remove everything that is not a letter or a digit (spaces, commas and other symbols).
Return true if the string s is a palindrome in this sense, and false otherwise.
Examples
Example 1:
Input: s = "Madam, in Eden, I'm Adam"
Output: true
Explanation: After clean-up the text is "madaminedenimadam". It reads the same in both directions.
Example 2:
Input: s = "Not a palindrome"
Output: false
Explanation: After clean-up the text is "notapalindrome". It does not read the same in both directions.
Example 3:
Input: s = "?!"
Output: true
Explanation: After clean-up nothing is left. An empty text reads the same in both directions.