A phrase is a palindrome if, after converting all uppercase letters into lowercase letters and removing all non-alphanumeric characters, it reads the same forward and backward. Alphanumeric characters include letters and numbers.
Given a string s, return true if it is a palindrome, or false otherwise.
Example 1:
- Input: s = “A man, a plan, a canal: Panama”
- Output: true
- Explanation: “amanaplanacanalpanama” is a palindrome.
Example 2:
- Input: s = “race a car”
- Output: false
- Explanation: “raceacar” is not a palindrome.
Example 3:
- Input: s = “ “
- Output: true
- Explanation: s is an empty string “” after removing non-alphanumeric characters. Since an empty string reads the same forward and backward, it is a palindrome.
Constraints:
- 1 <= s.length <= 2 * 105
- s consists only of printable ASCII characters.