LeetCode--5. Longest Palindromic

陆陆续续在LeetCode上刷了一些题，一直没有记录过，准备集中整理记录一下

class Solution {
    public String longestPalindrome(String s) {
         int n = s.length() - 1;
        while (n >= 0) {
            for (int i = 0; i + n < s.length(); i++) {
                String str = s.substring(i, i + n + 1);
                if (isPalindrome(str)) {
                    return str;
                }
            }
            n--;
        }
        return "";
    }


    private static boolean isPalindrome(String str) {
        int start = 0;
        int end = str.length() - 1;
        while (start < end) {
            if (str.charAt(start) != str.charAt(end)) {
                return false;
            }
            start++;
            end--;
        }
        return true;
    }
}