Write a C program that plays the logic game "Bulls and Cows."

The rules of the game are described here:
http://en.wikipedia.org/wiki/Bulls_and_cows

<< Wikipedia Quite >>

On a sheet of paper, the players each write a 4-digit secret number. The digits
must be all different. Then, in turn, the players try to guess their opponent's
number who gives the number of matches. If the matching digits are on their 
right positions, they are "bulls", if on different positions, they are "cows". 
Example:

    * Secret number:  4271
    * Opponent's try: 1234
    * Answer: 1 bull and 2 cows. (The bull is "2", the cows are "4" and "1".)

The first one to reveal the other's secret number wins the game. As the "first 
one to try" has a logical advantage, on every game the "first" player changes. 
In some places, the winner of the previous game will play "second". Sometimes, 
if the "first" player finds the number, the "second" has one more move to make 
and if he also succeeds, the result is even.

The secret numbers for bulls and cows are usually 4-digit-numbers, but the game
 can be played with 3 to 6 digit numbers (in every case it is more difficult 
than with 4).

<< END Quote >>

For this assignment assume that the game is played with only 4 digits
and the secret number cannot have repeated digits in it (e.g., 1013, 2245,
and 9999 are invalid secret numbers).

The program must print who wins and how many guesses it took to win.

Submit two versions of the program
  * Version 1: The user tries to guess the computer's number
               The computer just "thinks" of a random 4 digit number
               and then returns the number of "bulls" and "cows" for
               each of the user's guesses.

  * Version 2: The computer tries to guess the user's number
               Here the computer does the playing by trying the
               guess the user's secret number. The user enters
               the number of cows and bulls for each of the computer's guesses.


If you feel adventurous you can even write version 3 in which the computer 
plays against itself using the same code.

Submit on WebCT under "Extra Credit Homework"