For my class I have to write a program that will solve for the GCD of two non-zero integers. I have to do so using the euclidean algorithm:

Number 1: x
Number 2: y

1. Subtract x from y until y < x
2. Swap the values of x and y.
3. Repeat the steps 1 and 2 until x = 0
4. y is the gcd.

Also, I must put the calculation for finding the divisor in a static method.

My teacher doesn't so much as teach us how to program as she does read from the book. So I'm having some difficulty self-learning.

What I have so far:

public static void main(String[] args)
{

Scanner sc = new Scanner(System.in);
System.out.println("Greatest Common Divisor Finder");
String answer = "y";

while (answer.equalsIgnoreCase("y"))
{
System.out.print("Enter First number: ");
int firstNumber = sc.nextInt();
System.out.print("Enter Second number: ");
int secondNumber = sc.nextInt();
}
}

Now I'm working on the next method to find the divisor, and I know logically what I want to do, but I'm just not sure how to do it.
The way I see it, I need subtract x from y until it's zero, seems simple enough but I'm not sure where to go. Is there a difference between using an if or a while statement here?

If I had to take a guess, I would try a while loop,
while ( (x-y) != 0)
{
int difference = x - y
}

What I don't know is how i'll flip flop the x and y once y is less than x.

Any help would be greatly appreciated!

hows that?

Yours would work carteblanche, but doesn't use the euclidean algorithm.

This should work:



This post was edited by Kimano on Oct 21 2012 12:49pm

cartblance, your solution is the one I was able to find online and seems the best, but my teacher wanted the euclidean method for whatever reason.

Kimano, thanks so much! I was just having difficulty seeing how it would loop, but I think I get it now.

The technique they showed is called recursion and it's handy.