Question

Write a recursive method public static int sumEveryOther(int n) that takes a positive int as an argument and returns the sum of every other int from n down to 1.

For example, the call sumEveryOther(10) should return 30, since 10 + 8 + 6 + 4 + 2 = 30.

The call sumEveryOther(9) should return 25 since 9 + 7 + 5 + 3 + 1 = 25.

Your method must use recursion.

Answer 1

public static int sumEveryOther(int n) {
    if (n > 0) {
        return n + sumEveryOther(n - 2);
    }
    return 0;
}

public class SumEveryOther {

    public static int sumEveryOther(int n) {
        if (n > 0) {
            return n + sumEveryOther(n - 2);
        }
        return 0;
    }

    public static void main(String[] args) {
        System.out.println(sumEveryOther(10));
        System.out.println(sumEveryOther(9));
    }
}