1. Sit-In Lab 1 Twenty-Forty-Eight

2. 2048 Puzzle
4 by 4 matrix
You can slide the tiles in 4 directions: up, down, left, right
Tiles will hit each other
If 2 same-number tiles hit each other, they are “merged”
Tiles can only be merged once
Write a piece of code to print the result of the move
Input:
4 lines of 4 numbers - Initial state of the puzzle
Followed by d - the direction of the move
0 (left)
1 (up)
2 (right)
3 (down)
Output the outcome of the move

3. Sample 1 2 4 16 8 64 32
Move left

4. Similar numbers will be merged
Sample 1 2 4 16 8 64 32 4 16 8 2 64 32
Move left
Similar numbers will be merged
Before
After

5. Sample 2 2 4 16 8 64 32
Move up

6. Sample 2 2 4 16 8 64 32 2 16 8 4 64 32
Move up
Numbers take the place of the “0”
Similar numbers will be merged
Before
After

7. Sample 3 2 4 16 8 64 32
Move right

8. Sample 3 2 4 16 8 64 32 4 16 8 2 64 32
Move right
Numbers take the place of the “0”
Similar numbers will be merged
Before
After

9. Sample 4 2 4 16 8 64 32
Move down

10. Similar numbers will be merged
Sample 4 2 4 16 8 64 32 2 4 16 8 64 32
Move down
Similar numbers will be merged
Before
After

11. Algorithm #1 To move up… Use a combination of rotateRight moveLeft 216 8 4 64 32 4 8 32 64 16 2
Use a combination of
rotateRight
moveLeft
4. Move left
To move up…
1. Rotate right
2. Rotate right
3. Rotate right 2 4 16 8 64 32 32 2 4 64 16 8 64 32 4 2 8 16 2 4 8 32 64 16

12. Algorithm #1 To move right… Use a combination of rotateRight moveLeft4 16 8 2 64 32 4 2 64 8 32 16
Use a combination of
rotateRight
moveLeft
4. Rotate right
To move right…
1. Rotate right
2. Rotate right
3. Move left 2 4 16 8 64 32 32 2 4 64 16 8 64 32 4 2 8 16 64 4 32 2 8 16

13. Algorithm #1 To move down… Use a combination of rotateRight moveLeft 24 16 8 64 32 4 8 32 64 16 2
Use a combination of
rotateRight
moveLeft
4. Rotate right
To move down…
1. Rotate right
2. Move left
3. Rotate right 2 4 16 8 64 32 32 2 4 64 16 8 32 2 4 64 16 8 8 64 32 4 2 16

14. Main method Helper methods Read in the inputs
Call helper methods and print the output
Helper methods
rotateRight: rotate the matrix 90 degrees right
moveLeft: move numbers to the left, merging numbers if necessary

15. Algorithm #2 Assemble 1D array Perform moveLeft on each of the array
Copy result back to array 1 2 3 4 4 3 2 1
Move left
Move right 1 2 3 4 4 3 2 1
Move up
Move down

16. Main method Helper methods Read in the inputs
Call helper methods and print the output
Helper methods
assemble1DArray: retrieve 1D array based on direction of move, set first element to be the direction of the move
moveLeft: move numbers to the left, merging numbers if necessary

17. How to assemble?

18. 2 4 16 8 64 32 Sample 1 Move left [0, 0] [0, 1] [0, 2] [0, 3] …4 16 8 64 32
Move left
(first element is the direction of the move)
[0, 0]
[0, 1]
[0, 2]
[0, 3] …

19. Sample 2 2 4 16 8 64 32
Move up
[0, 0]
[1, 0]
[2, 0]
[3, 0] …

20. Sample 3 2 4 16 8 64 32
Move right
[0, 3]
[0, 2]
[0, 1]
[0, 0] …

21. Sample 4 2 4 16 8 64 32
Move down
[3, 0]
[2, 0]
[1, 0]
[0, 0] …

22. How to collapse and merge?
(moveLeft)

23. moveLeft 2 4
Move left
Collapse all numbers to left 2 4

24. 2 4 2 4 moveLeft Compare 2 numbers if similar
If not, move onto the next set of numbers 2 4

25. 2 4 2 8 moveLeft Compare the next set of numbers
If yes, merge the numbers 2 8

26. 2 8 2 8 moveLeft Continue until no more comparisons
Collapse everything to the left again, if necessary 2 8

27. Questions?