[Solved] Recursive definition solution

Question

To get a working recursive solution you need a base case, for example a == 0, and then work yourself down towards the base case by recursively calling yourself.

The solution for question 1 could be something along the lines of this, that decreases the a argument until it reaches 0:

int multiply(int a, int b) {
    if (a == 0 || b == 0) {
        return 0;
    } 
    return b + multiply(a - 1, b);
}

For example, multiply(2, 5) would become 5 + multiply(1, 5) -> 5 + 5 + multiply(0, 5) -> 5 + 5 + 0.

Note that this particular solution doesn’t work for negative numbers, but you get the idea. You should be able to easily add support for that yourself.

Accepted Answer

To get a working recursive solution you need a base case, for example a == 0, and then work yourself down towards the base case by recursively calling yourself.

The solution for question 1 could be something along the lines of this, that decreases the a argument until it reaches 0:

int multiply(int a, int b) {
    if (a == 0 || b == 0) {
        return 0;
    } 
    return b + multiply(a - 1, b);
}

For example, multiply(2, 5) would become 5 + multiply(1, 5) -> 5 + 5 + multiply(0, 5) -> 5 + 5 + 0.

Note that this particular solution doesn’t work for negative numbers, but you get the idea. You should be able to easily add support for that yourself.