0005. Longest Palindromic Substring

class Solution {
    
    public static String longestPalindrome(String s) {
        int n = s.length();
        int l = 0, r= 0;
        String res = "";
        for (int i = 0; i < n; i++) {
            //abba
            l = i;
            r = i + 1;
            while (l > -1 && r < n && s.charAt(l) == s.charAt(r)) {
                l--;
                r++;
            }
            if (r - l - 1 > res.length()) {
                res = s.substring(l + 1, r);
            }
            //aba
            l = i - 1;
            r = i + 1;
            while (l > -1 && r < n && s.charAt(l) == s.charAt(r)) {
                l--;
                r++;
            }
            if (r - l - 1 > res.length()) {
                res = s.substring(l + 1, r);
            }
        }
        return res;
    }
}