class Solution {
public:
    bool isPalindrome(string s) {
        string new_s = "";
        for (auto ch: s){
            if (isalnum(ch))
                new_s += tolower(ch);
        }

        int left = 0;
        int right = new_s.size() - 1;
        while (left < right){
            if (new_s[left] !=new_s[right]){
                return false;
            }
            left++;
            right--;
        }
        return true;
    }
};