longestPalindrome

longestPalindrome1.java

class Solution {
    public String longestPalindrome(String s) {
        if (s == null || s.length() == 0) {
            return "";
        }
        String longest = "";
        for (int i = 0; i < s.length(); i++) {
            if (i < s.length() - 1 && s.charAt(i) == s.charAt(i + 1)) {
                String temp1 = find(s, i, i + 1);
                if (temp1.length() > longest.length()) {
                    longest = temp1;
                }
            }
            String temp2 = find(s, i, i);
            if (temp2.length() > longest.length()) {
                longest = temp2;
            }
        }
        return longest;
    }
    
    private String find(String s, int start, int end) {
        String longest = s.substring(start, end + 1);
        while (start - 1 >= 0 && end + 1 < s.length()
               && s.charAt(start - 1) == s.charAt(end + 1)) {
            longest = s.substring(start - 1, end + 2);
            start = start - 1;
            end = end + 1;
        }
        return longest;
    }
}