求1+2+3+···+··n,不能使用x和/,for,if,while,switch
import java.util.Scanner;
public class Demo_65 {
public static void main(String[] args) {
int res = new Demo_65().getSum(new Scanner(System.in).nextInt());
System.out.println(res);
}
private int getSum(int n) {
return n > 0 ? n + getSum(n-1) : 0;
}
}