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Problem: Valid Palindrome

Explore how to determine if a string is a valid palindrome by converting letters to lowercase and skipping non-alphanumeric characters. Learn to implement an efficient two-pointer algorithm that compares characters from both ends without extra space, improving your skills in string manipulation and algorithmic problem-solving.

Statement

A phrase is considered a palindrome if, after converting all uppercase letters to lowercase and stripping all non-alphanumeric characters, it reads the same forward and backward. Alphanumeric characters include both letters and numbers.

Given a string s, return true if it qualifies as a palindrome after the transformations described above, or false otherwise.

Note: An empty string (which may result after removing all non-alphanumeric characters) is considered a palindrome.

Constraints:

  • 11 \leq s.length 2×105\leq 2 \times 10^5 ...