public static int fact(int n) {
// ---------------------------------------------------
// Computes the factorial of a nonnegative integer.
// Precondition: n must be greater than or equal to 0.
// Postcondition: Returns the factorial of n.
// ---------------------------------------------------
   if (n == 0) {
     return 1;
   } 
   else {
     return n * fact(n-1);
   }  // end if
}  // end fact