Dart package for generating and solving Sudoku puzzles.

Puzzles with dimensions 4, 9, 16 and 25 are supported. The dimensions are the number of positions on each group of the puzzle.

The most usual (and default) dimension, 9, generates puzzles composed of 9 3x3 groups. Each group will have 9 positions to be filled by numbers from 1 to 9.

Similarly, puzzles with dimension 16 will be composed of 16 4x4 groups. Each group has 16 positions to be filled by numbers from 1 to 16.

At least for now, the PuzzleDifficulty enumeration only influences the number of empty positions in generated puzzles of dimensions 4 and 9. For bigger puzzles, if the number of empty positions isn't limited to a ceiling value (currently 81), the time to generate a single puzzle tends to become too long (in the order of several minutes).

Tests

Unit tests are available for the board, generator, and solver libraries.

Use either dart test or flutter test to run the tests.

Example

An usage example for the package:


import 'package:fludoku/fludoku.dart';

void main() {
  var board = Board();
  board.setAt(row: 0, col: 0, value: 4);
  board.setAt(row: 3, col: 1, value: 6);
  try {
    board.setAt(row: 1, col: 2, value: 4);
  } on ArgumentError catch (e) {
    print('Exception: $e');
  }
  final valueSet = board.trySetAt(row: 1, col: 2, value: 4);
  assert(valueSet == false);
  print('board:\n$board\n');

  var smallPuzzle = generateBoard(PuzzleDifficulty.hard, 4);
  print("Small puzzle:\n$smallPuzzle\n");
  var smallPuzzleSolution = findSolutions(smallPuzzle);
  print("Small puzzle solution:\n$smallPuzzleSolution\n");

  var puzzle = generateBoard(PuzzleDifficulty.hard, 9);
  print("Puzzle:\n$puzzle\n");
  var puzzleSolution = findSolutions(puzzle);
  print("Puzzle solution:\n$puzzleSolution\n");

  var bigPuzzle = generateBoard(PuzzleDifficulty.medium, 16);
  print("Big puzzle:\n$bigPuzzle\n");
  var bigPuzzleSolution = findSolutions(bigPuzzle);
  print("Big puzzle solution:\n$bigPuzzleSolution\n");
}

The output of the example program:

❯ dart run example/fludoku_example.dart
Exception: Invalid argument(s): Cannot set (1, 2) to "4" as it would invalidate the board
board:

 4  -  -    -  -  -    -  -  -
 -  -  -    -  -  -    -  -  -
 -  -  -    -  -  -    -  -  -


 -  6  -    -  -  -    -  -  -
 -  -  -    -  -  -    -  -  -
 -  -  -    -  -  -    -  -  -


 -  -  -    -  -  -    -  -  -
 -  -  -    -  -  -    -  -  -
 -  -  -    -  -  -    -  -  -


Small puzzle:

 3  4    1  -
 1  -    -  -


 -  -    -  1
 -  -    4  -


Small puzzle solution:
[
 3  4    1  2
 1  2    3  4


 4  3    2  1
 2  1    4  3
]

Puzzle:

 -  8  2    4  9  6    -  -  -
 3  -  -    1  -  -    -  -  6
 -  -  -    -  -  2    -  1  -


 8  3  -    -  -  -    5  2  -
 -  -  -    2  -  -    1  3  8
 2  7  5    -  -  -    4  -  9


 4  -  7    6  -  5    -  -  1
 5  -  -    -  -  -    6  4  -
 -  -  -    -  -  -    -  -  5


Puzzle solution:
[
 1  8  2    4  9  6    7  5  3
 3  5  4    1  7  8    2  9  6
 7  6  9    5  3  2    8  1  4


 8  3  1    9  6  4    5  2  7
 9  4  6    2  5  7    1  3  8
 2  7  5    8  1  3    4  6  9


 4  9  7    6  2  5    3  8  1
 5  1  3    7  8  9    6  4  2
 6  2  8    3  4  1    9  7  5
]

Big puzzle:

 8 12 15  3    9 11 13  1    6  - 10  7    -  5  -  4
 - 11 13  1   14 12  -  3    8  5 16  4    6  - 10  7
 6  2 10  -    -  5  -  4    - 12 15  3    9 11 13  -
 -  -  -  -    6  2 10  7    - 11 13  -    -  - 15  3


12 14  3  -    -  9  1  -    -  -  7 10    -  -  - 16
11  9  1  -   15 14 12  -    5  8  - 16    3 10  -  2
 -  6  - 10    5  8  - 16   12 14  3  -    -  9  1 13
 -  8  4  -    3 10  -  2   11  -  1 13   12 14  6 15


15  - 14  9   12 13  - 10    1  7  -  2    -  4  8  5
 -  - 12  -    2  - 14  9   16  4  8  5   10  7  3  6
 -  -  -  8    -  4  3  5   15 13  - 12    2  1  9 11
16  -  2  5    -  7  -  8    - 10  - 11    - 13 14 12


 3 15  -  -    -  1  - 12    7 16 11  8    4  -  5 10
 - 13 11  -    -  3  9  -    4  -  5  6    7 16  2  8
 7 10  8  6    4  -  - 11   13  3  2  -    1 15  -  -
 4 16  -  2    7  6  8  -   10  1  -  9   13  - 11 14


Big puzzle solution:
[
 8 12 15  3    9 11 13  1    6  2 10  7   14  5 16  4
 9 11 13  1   14 12 15  3    8  5 16  4    6  2 10  7
 6  2 10  7    8  5 16  4   14 12 15  3    9 11 13  1
14  5 16  4    6  2 10  7    9 11 13  1    8 12 15  3


12 14  3 15   11  9  1 13    2  6  7 10    5  8  4 16
11  9  1 13   15 14 12  6    5  8  4 16    3 10  7  2
 2  6  7 10    5  8  4 16   12 14  3 15   11  9  1 13
 5  8  4 16    3 10  7  2   11  9  1 13   12 14  6 15


15  3 14  9   12 13 11 10    1  7  6  2   16  4  8  5
13  1 12 11    2 15 14  9   16  4  8  5   10  7  3  6
10  7  6  8   16  4  3  5   15 13 14 12    2  1  9 11
16  4  2  5    1  7  6  8    3 10  9 11   15 13 14 12


 3 15  9 14   13  1  2 12    7 16 11  8    4  6  5 10
 1 13 11 12   10  3  9 14    4 15  5  6    7 16  2  8
 7 10  8  6    4 16  5 11   13  3  2 14    1 15 12  9
 4 16  5  2    7  6  8 15   10  1 12  9   13  3 11 14
]


fludoku on  main [!+⇡] is 󰏗 v1.0.0 via  v3.5.3 took 13s
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Libraries

fludoku
Generates and solves Sudoku puzzles with dimensions 4, 9 (default), 16, or 25.