Valid Palindrome
EASYTwo PointersA 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.
Examples
Example 1
Input: s = "A man, a plan, a canal: Panama"
Output: true
"amanaplanacanalpanama" is a palindrome.
Example 2
Input: s = "race a car"
Output: false
"raceacar" is not a palindrome.
Example 3
Input: s = " "
Output: true
s is an empty string "" after removing non-alphanumeric characters. An empty string reads the same forward and backward.
Constraints
- 1 <= s.length <= 2 * 10^5
- s consists only of printable ASCII characters.
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