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Valid Palindrome

EasyTwo Pointers

Given a string s, return True if it is a palindrome after converting all uppercase letters to lowercase and removing all non-alphanumeric characters, or False otherwise.

Example:

Input:
A man, a plan, a canal: Panama
Output:
True
Reasoning:
  • The input string "A man, a plan, a canal: Panama" is converted to lowercase, resulting in "a man, a plan, a canal: panama".
  • All non-alphanumeric characters (spaces, commas, colon) are removed from the string, yielding "amanaplanacanalpanama".
  • The resulting string is then checked to see if it's a palindrome by comparing characters from the start and end, moving towards the center.
  • Since "amanaplanacanalpanama" reads the same forwards and backwards, the function returns True.

Constraints:

  • 1 <= len(s) <= 2 * 10^5
  • s consists only of printable ASCII characters
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Test Results

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