Question

I want to find GCD of two numbers but without using division or mod operator.
one obvious way would be to write own mod function like this:

enter code here
int mod(int a, int b)
{
   while(a>b)
       a-=b;

return a;
}

and then use this function in the euclid algorithm.
Any other way ??

Answer 1

You can use the substraction based version of euclidean algorithm up front:

function gcd(a, b)
    if a = 0
       return b
    while b ≠ 0
        if a > b
           a := a − b
        else
           b := b − a
    return a