Programming Job Interview Challenge

I just found a very interesting Series on http://www.dev102.com.
They feature a Series about Questions in Job Interviews. There were already 3 Challenges.

Because the last part wasn’t that easy this part is all about simplicity.

This week’s challenege can be found here

The Task:

How would you implement the following method:
Foo(7) = 17 and Foo(17) = 7.
Any other input to that method is not defined so you can return anything you want. Just follow those rules:

• Conditional statements (if, switch, …) are not allowed.

• Usage of containers (hash tables, arrays, …) are not allowed.

The Answer:
So you need a function which takes in an integer value and returns a simple integer value.
This sound’s like a simple linear math function.
The function can be found relative easily.
f(7) = 17
f(17) = 7

so

7 + 17 = 24
17 + 7 = 24

There we have the connection between the value pairs so the calculation would be
f(x) = 24 – x;

in C# I would write the method as following:

int Foo(int x)

{

    return 24 - x;

}

So this would be my solution for the task.