从右边枚举找到最短的回文串

import java.io.*;

public class Main {
    static BufferedReader bw = new BufferedReader(new InputStreamReader(System.in));
    static PrintWriter pw = new PrintWriter(new BufferedWriter(new OutputStreamWriter(System.out)));
    public static void main(String[] args) throws Exception{
        String str = bw.readLine();
       if(str.length() == 1) System.out.println(str);
       else {
           for (int i = str.length() - 1; i >= 0; i--) {
               if(aaa(str, i)){
                   pw.print(new StringBuffer(str.substring(i + 1)).reverse());
                   break;
               }
           }
           pw.println(str);
           pw.flush();
       }

    }
    public static boolean aaa(String str, int i){
        for (int j = 0; j <= i / 2; j++) {
            if(str.charAt(j) != str.charAt(i - j)) return false;
        }
        return true;
    }
}