can any one help figure this out using python?

Design a recursive function that accepts two arguments into the parameters x and y. The function should return the value of x times y. Assume that x and y will always be positive nonzero integers. Remember, multiplication开发者_开发问答 can be performed as repeated addition as follows: 8 x 7 = 8 + 8 + 8 + 8 + 8 + 8 + 8

def my(x,y):
    if x==0:
        return 0

    else:

        return x*mul(x,x-1)
assertEqual(my(8,7),56)
assertEqual(my(8,5),40)
assertEqual(my(8,2),16)

Here's some pseudo-code that should do the trick:

define mult(x,y):
    if x is zero:
        return zero
    return y plus mult(x-1, y)

Now, because I've always thought that Python is an ideal pseudo-code language, that should be fairly easy to convert. The idea with recursion is to define an operation in terms of simpler operations and provide a terminating one.

In order to understand this, imagine what happens when x is 3 and y is 7.

First time in mult(3,7), x is non-zero so the result is y (= 7) plus mult(2,7).

For mult(2,7): result is y (= 7) plus mult(1,7).

For mult(1,7): result is y (= 7) plus mult(0,7).

For mult(0,7): result is zero since x is zero.

This gives you (7 + (7 + (7 + (0)))) or 21, as expected.