- import java.util.Scanner;
- public class JPA03 {
- public static void main(String[] args) {
- Scanner sc=new Scanner(System.in);
- int n;
- try{
- n=sc.nextInt();
- if(n==0){
- System.out.println("error");
- return;
-
- }
- n=Math.abs(n);
- System.out.println(compute(n));
- }catch(Exception e){
- System.out.println("error");
- return;
- }
- }
- public static int compute(int i){
-
- if(i==1)
- return 2;
- else
- return compute(i-1)+3*i;
- }
- }
複製代碼 |