Question from category: is any difference?

The main actions that we need to enable are movements left, right, up and down.
If you've already played 2048, then you know that when you move in a direction, tiles with values move to empty tiles, and tiles with the same value combine.

As a basic scenario, let's consider movement to the left and think about what happens when we want to do this action.

For each row or column, two things actually happen:
a) Consolidate the tiles so that all the empty tiles are on the right, i.e. the row {4, 2, 0, 4} becomes {4, 2, 4, 0}
b) Merge tiles with the same value, i.e. the row {4, 4, 2, 0} becomes {8, 2, 0, 0}.
Note that the row {4, 4, 4, 4} will become {8, 8, 0, 0}, and {4, 4, 4, 0} becomes {8, 4, 0 , 0}.

Create consolidateTiles(Tile[] tiles) and mergeTiles(Tile[] tiles) methods that implement steps a) and b) respectively. We will use them only inside the Model class, so give them the narrowest possible access.

Also, add int score and int maxTile fields, which should store the current score and the highest tile weight on the game board. The score increases after each merger. For example, if the current score is 20 and the row {4, 4, 4, 0} is merged, then the score should increase by 8. The access level for these fields should be wider than private.
The easiest thing to do is to update these fields in the mergeTiles method, for example:
1) If the tile merger condition is satisfied, check whether the new value is greater than the maximum value and, if necessary, change the value of the maxTile field.
2) Increase the value of the score field by the amount of the tile weight generated by the merger.

P.S. When we implement the movement methods, tiles will always be consolidated before they are merged, so you can assume that the mergeTiles method will always be passed an array of tiles that does not have empty tiles in the middle.