Algorithms | Divide and Conquer | Question 2

Consider the following C program

int main()
{
   int x, y, m, n;
   scanf ("%d %d", &x, &y);
   /* x > 0 and y > 0 */
   m = x; n = y;
   while (m != n)
   {
      if(m>n)
         m = m - n;
      else
         n = n - m;
   }
   printf("%d", n);
}

What does the program compute? (GATE CS 2004)
(A) x + y using repeated subtraction
(B) x mod y using repeated subtraction
(C) the greatest common divisor of x and y
(D) the least common multiple of x and y

Answer: (C)
Explanation: This is an implementation of Euclid’s algorithm to find GCD