C语言程序设计教程（第三版）课后习题5.5 （Java代码）

import java.util.Scanner;

public class Main {

        public static int XY(int x){

                if(x<1)

                        return x;

                if(1<=x&&x<10)

                        return 2*x+1;

                if(x>=10)

                        return 3*x-11;

       return 1;

        }

        public static void main(String[] arg){

                Scanner sc = new Scanner(System.in);

                int x = sc.nextInt();

                System.out.print(XY(x));

        }

}