hihoCoder求最长回文字符串

程序如下：
import java.util.Scanner;
public class Main {
public static void main(String[] args) {

                String str = "";
                Scanner in = new Scanner(System.in);
                int max=0;      //存放最大长度
                String longestPalindrome="";     //存放最长回文
                str = in.nextLine(); 
                int length = str.length();  

                for (int i = 0; i < length; i++) {         //遍历所有子串
                    for (int j = i + 1; j < length; j++) {  
                        int len = j - i;  
                        String curr = str.substring(i, j + 1);  
                        if (isPalindrome(curr)) {  
                            if (len > max) {  
                                longestPalindrome = curr;  
                                max = len;  
                            }  
                        }  
                    }  
                }  

                return longestPalindrome;  
            }  

            public static boolean isPalindrome(String s) {       //判断是否为回文

                for (int i = 0; i < s.length() - 1; i++) {  
                    if (s.charAt(i) != s.charAt(s.length() - 1 - i)) {  
                        return false;  
                    }  
                }  

                return true;  
            }  
        }