int n = in.nextInt(); String s = in.next(); System.out.println(new StringBuffer(s).reverse().toString());
import java.util.Scanner; // 注意类名必须为 Main, 不要有任何 package xxx 信息 public class Main { public static void main(String[] args) { Scanner in = new Scanner(System.in); int n = 0; String s = ""; if (in.hasNextInt()) { n = in.nextInt(); } if (in.hasNext()) { s = in.next(); } char[] a = s.toCharArray(); for (int i=n-1;i>=0; i--){ System.out.print(a[i]); } } }