题解 | 牛牛学数列4

import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        int n = scanner.nextInt();
        int result = arithmetic (n);
        System.out.printf("%d", result);
        scanner.close();
    }

    private static int arithmetic (int n) {
        if (n == 0) {
            return 0;
        } else {
            int m = n;
            int sum = 0;
            while (m > 0) {
                sum += m--;
            }
            return sum + arithmetic (n - 1);
        }
    }
}

递归实现