Ball sort puzzle is that offline game, there is also another form of this game called water sort puzzle. In the game there are n stacks containing different colors of balls. There are 4 balls of each color and in total 4n balls. Out of that, there are 2 empty stakes provided for the players to sort the balls by their color. In the sorting process several basic principles need to be followed.
- only top ball of each stake can be removed
- a ball can be left on another if they are the same color (except the situation that this stake is empty)
I am wondering why there are only two empty stakes provided no matter how many colors of balls are there? Or is there always a solution to the game no matter the value of n is large or small?