Question

JAVA

3. Write a recursive method to compute: xº + x1 + x2 + ... + xn 4. Write a recursive method for sum of the non-negative even numbers less than n. (Try to use a helper method for this one) Now modify your methods to print the non-negative even numbers less than n.

Answer 1

3)

public static double compute(double x, int n) {
    if (n == 0) {
        return 1;
    }
    return Math.pow(x, n) + compute(x, n-1);
}

4)

public static int sum(int n) {
    if (n == 0) {
        return n;
    }
    if (n % 2 == 0) {
        return n + sum(n-2);
    } else {
        return sum(n-1);
    }
}

public static void printEven(int n) {
    if (n == 0) {
        System.out.println(0);
    }
    if (n % 2 == 0) {
        System.out.println(n);
        printEven(n-2);
    } else {
        printEven(n-1);
    }
}