#125

Valid Palindrome

Easy
Two PointersString

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*.

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. Since an empty string reads the same forward and backward, it is a palindrome.

Constraints

  • 1 <= s.length <= 2 * 10^5
  • s consists only of printable ASCII characters.
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