1. Open the provided arrayMax.c file and write
    the function:
      int * arrayMax(int * array, int n);
    which returns a pointer to the largest element
    in the array passed in (whose length is n).
    If the array has no elements (n is 0), this function
    should return NULL.

 2. Compile and test your code. 
    We have provided a main function which will print test cases
    and your function's answer for them. You should get
    99, -3, 425, NULL, and NULL for the 5 test provided.

 3. Submit your code.