There is a Java program that is missing one recursivefunction:
public class GCD {
/* There is a neat trick with recursive programming. Thefunction described
  * below requires that y is at most x. Rather thanadd this to the recursive
  * function definition, we can add a front-end,helper function.
  *
  * I wrote this function for you and I called itgcd. The recursive logic goes
  * in a function called gcd_rec. All gcd does ismake sure that x is not
  * smaller than y.   Â
  */
/* Requires x >= y
  *           /x           when y is 0
  * gcd(x,y) = |
  *           \gcd(y, x%y) otherwise
  */
public static int gcd_rec(int x, int y) {
   return 0;
}
public static int gcd(int x, int y) {
   if(x < y)
     return gcd_rec(y,x);
   else
     return gcd_rec(x,y);
}
/* Greatest Common Divisor Test Framework
  */
public static void main(String[] args) {
   int[] inputX = {10, 35, 14, 4181};
   int[] inputY = { 8, 15, 35, 6765};
   int[] expect = { 2, 5, 7,   1};
   boolean error = false;
   assert(inputY.length == inputX.length);
   for(int i = 0 ; i < inputX.length; i++){
     int answer = gcd(inputX[i],inputY[i]);
     if(answer != expect[i]) {
       System.out.printf(\"ERROR: gcd(%d,%d) returned %d not %d.\n\",
                         inputX[i], inputY[i], answer, expect[i]);
       error = true;
     }
   }
   if(error)
     System.exit(1);
   else
     System.out.println(\"GoodJob!\");
}
}
