Valid Palindrome

class Solution:
    def isPalindrome(self, s: str) -> bool:
        filtered = ''.join(char.lower() for char in s if char.isalnum())
        return filtered == filtered[::-1]

class Solution {
public:
    bool isPalindrome(string s) {
        string filtered;
        for (char c : s) {
            if (isalnum(c)) {
                filtered += tolower(c);
            }
        }
        string reversed = filtered;
        reverse(reversed.begin(), reversed.end());
        return filtered == reversed;
    }
};

function isPalindrome(s: string): boolean {
    const filtered = s.replace(/[^a-zA-Z0-9]/g, '').toLowerCase();
    return filtered === filtered.split('').reverse().join('');
}