Statistics

Problem Statement for "BearDestroysDiv2"

Problem Statement

Limak is a big grizzly bear. He is now going to destroy an entire forest.


Limak's forest is a rectangular grid that consists of W columns by H rows of cells. At the beginning a single tree grows in each cell. The forest is aligned with the major compass directions: row numbers increase towards the South and column numbers increase towards the East.


Limak will destroy the forest by pushing some of the trees. Whenever Limak pushes a tree, the tree will fall down and remain lying both in the current cell and in the next cell in the direction in which it was pushed. For example, if Limak pushes the tree that grows in the cell (r,c) southwards, he will obtain a toppled tree that lies in the cells (r,c) and (r+1,c).


When pushing the trees, Limak always follows a few rules:

  • He only pushes trees in two directions: either southwards or eastwards.
  • He will never push a tree in a way that would cause it to fall out of the forest. For example, he will never push a tree in the last column eastwards.
  • He will never push a tree in a way that would produce two fallen trees lying on the same cell.


There is a single letter written on each of the trees. Each of these letters is either S or E (representing South and East, respectively). When pushing a tree, Limak will prefer the direction that is written on the tree. For example, if a tree has the letter S, Limak will push it southwards if possible.


Limak is going to visit each cell in the forest exactly once, in row major order. I.e., first he will visit all the cells in the first row from left to right, then the cells in the second row from left to right, and so on. In each cell he will act according to the following algorithm:


  1. Is there a fallen tree in the current cell? If yes, there is no room here to do anything, so I'll just move to the next cell.
  2. Can I push the tree in the direction that is given by the letter written on the tree? If yes, I'll do so and move to the next cell.
  3. Can I push the tree in the other direction? If yes, I'll do so and move to the next cell.
  4. I'll move to the next cell without pushing the tree.


See Example 0 for a sample execution of Limak's algorithm.


You are given the ints W and H. There are 2^(W*H) different forests with these dimensions. (Different forests have different assignments of letters S and E to the trees.) For each of these forests, compute the number of trees Limak would topple. Return the sum of those 2^(W*H) numbers, modulo MOD.

Definition

Class:
BearDestroysDiv2
Method:
sumUp
Parameters:
int, int, int
Returns:
int
Method signature:
int sumUp(int W, int H, int MOD)
(be sure your method is public)

Constraints

  • W will be between 1 and 7, inclusive.
  • H will be between 1 and 40, inclusive.
  • MOD will be between 3 and 10^9, inclusive.
  • MOD will be prime.

Examples

  1. 4

    3

    999999937

    Returns: 24064

    There are 2^(4*3) = 2^12 = 4096 different forests with W=4 columns and H=3 rows. One of those forests looks as follows: SEEE ESSS EESS When destroying this forest, Limak will push five trees. In the scheme below, the final locations of the toppled trees are shown using the numbers 1 through 5. The trees are numbered in the order in which Limak pushed them. The two cells that do not contain a fallen tree at the end are denoted by underscores. 1223 1453 _45_ It can be shown that for these dimensions there are exactly 512 forests in which Limak would topple exactly 5 trees. In each of the remaining (4096-512) forests Limak would topple 6 trees. Thus, the return value is 512 * 5 + (4096-512) * 6.

  2. 3

    4

    999999937

    Returns: 24576

    For these dimensions of the forest Limak will always topple exactly 6 trees. The return value is 6 * 2^12.

  3. 2

    20

    584794877

    Returns: 190795689

    For these dimensions of the forest Limak will always topple exactly 20 trees. The return value is (20 * 2^40) modulo MOD.

  4. 5

    10

    3

    Returns: 2

  5. 1

    1

    19

    Returns: 0

  6. 7

    40

    312880987

    Returns: 256117818

  7. 1

    1

    71876209

    Returns: 0

  8. 1

    2

    483128897

    Returns: 4

  9. 1

    3

    442951021

    Returns: 8

  10. 1

    4

    366999047

    Returns: 32

  11. 1

    5

    3

    Returns: 1

  12. 2

    1

    643643149

    Returns: 4

  13. 2

    2

    291474539

    Returns: 32

  14. 2

    3

    633529777

    Returns: 192

  15. 2

    4

    7

    Returns: 2

  16. 2

    5

    108313867

    Returns: 5120

  17. 3

    1

    975807823

    Returns: 8

  18. 3

    2

    232315729

    Returns: 192

  19. 3

    3

    11

    Returns: 2

  20. 3

    4

    253520207

    Returns: 24576

  21. 3

    5

    781548307

    Returns: 229376

  22. 4

    1

    73185317

    Returns: 32

  23. 4

    2

    257580319

    Returns: 1024

  24. 4

    3

    908346931

    Returns: 24064

  25. 4

    4

    110648963

    Returns: 522240

  26. 4

    5

    748527467

    Returns: 10354688

  27. 5

    1

    496986739

    Returns: 64

  28. 5

    2

    836042177

    Returns: 5120

  29. 5

    3

    11

    Returns: 4

  30. 5

    4

    3

    Returns: 1

  31. 5

    5

    13

    Returns: 11

  32. 1

    40

    13

    Returns: 8

  33. 7

    1

    246931759

    Returns: 384

  34. 2

    40

    543491279

    Returns: 305520570

  35. 7

    2

    431566237

    Returns: 114688

  36. 3

    40

    422344259

    Returns: 100200332

  37. 7

    3

    932041361

    Returns: 20938752

  38. 4

    40

    653858027

    Returns: 486979880

  39. 5

    40

    5

    Returns: 2

  40. 3

    33

    338057281

    Returns: 229234113

  41. 4

    10

    673227689

    Returns: 300090229

  42. 1

    2

    519275041

    Returns: 4

  43. 7

    20

    204635693

    Returns: 113263323

  44. 7

    3

    291198361

    Returns: 20938752

  45. 3

    27

    754290517

    Returns: 521712476

  46. 6

    12

    153692323

    Returns: 134236843

  47. 5

    15

    89654479

    Returns: 52084944

  48. 7

    1

    759804347

    Returns: 384

  49. 7

    24

    945707647

    Returns: 224739679

  50. 7

    40

    476882267

    Returns: 197168764

  51. 7

    39

    226092029

    Returns: 218121254

  52. 7

    38

    521517259

    Returns: 358484312

  53. 7

    37

    18861637

    Returns: 2388729

  54. 7

    36

    5

    Returns: 0

  55. 7

    35

    62988109

    Returns: 36393817

  56. 7

    34

    763736669

    Returns: 690035012

  57. 6

    40

    615400307

    Returns: 467682622

  58. 6

    39

    863998307

    Returns: 105866078

  59. 6

    38

    11

    Returns: 9

  60. 6

    37

    623550203

    Returns: 436670574

  61. 6

    36

    130471169

    Returns: 39616000

  62. 6

    35

    747432841

    Returns: 152857752

  63. 6

    34

    668902831

    Returns: 428552389

  64. 5

    40

    857873893

    Returns: 394867891

  65. 5

    39

    10639481

    Returns: 10034404

  66. 5

    38

    121972309

    Returns: 86849625

  67. 5

    37

    219726329

    Returns: 169427842

  68. 5

    36

    3

    Returns: 0

  69. 5

    35

    366586403

    Returns: 354218015

  70. 5

    34

    226377817

    Returns: 11359520

  71. 7

    40

    97837079

    Returns: 18106495

  72. 7

    40

    684074123

    Returns: 522878364

  73. 7

    40

    3

    Returns: 0

  74. 7

    36

    312880987

    Returns: 197986862

  75. 7

    39

    1000003

    Returns: 975462


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