Bulls And Cows / Guess Number

How to play:<br>1. Input a random numbers but not duplicated<br>2. You will get a hint by ?A?B, A means right position and right number, B means wrong position but right number.<br><br>For example: input 1234, you got 1A1B ,<br>It means you got 2 numbers, but one is in right position, the other isn't.<br><br>Function:<br>1. 3 - 8 digits length selectable<br>2. Press the restart bottom, then new game starts.