Sudoku 1.1.1

Sudoku

A fast Sudoku solver written in C#. Can also act as a Sudoku generator.

Usage in Code

Solving Sudokus

var puzzle = new int[81];

/*
  Fill the array with the puzzle here. Use 0 to represent empty cells.
  
  Just flatten the puzzle into one long sequence,
  so puzzle[0..8] is the first row, puzzle[9..17] is second and so on.
*/

var solver = new Solver();

var result = solver.Solve(puzzle);
        
/*
  Output to console with a left offset of 1.
  Store cursor y position to draw puzzle and solution side by side.
*/

var y = Console.CursorTop;

puzzle.DumpToConsole(1, y);
        
result.Solution.DumpToConsole(30, y);

// The result has additional informational properties.

result.Steps; // How many steps were explored to find the answer.

result.Microseconds; // How long it took to solve.

/*
  There is an option to get the order in which the answer was found.
  This isn't generated by default for performance reasons.
  If you would like the history, add true as a parameter to the Solve call...
*/

solver.Solve(puzzle, true);

foreach (var move in result.History)
{
    Console.WriteLine($"Row: {move.Y}    Column: {move.X}    Value: {move.Value}");        
}

Output:

 ┌───────┬───────┬───────┐    ┌───────┬───────┬───────┐
 │       │   2   │   9   │    │ 4 5 7 │ 8 2 6 │ 1 9 3 │
 │   6   │ 1     │       │    │ 9 6 3 │ 1 4 5 │ 2 8 7 │
 │     2 │ 7 3   │ 6     │    │ 8 1 2 │ 7 3 9 │ 6 5 4 │
 ├───────┼───────┼───────┤    ├───────┼───────┼───────┤
 │   3   │ 4     │ 8     │    │ 2 3 1 │ 4 5 7 │ 8 6 9 │
 │ 7 8   │ 6 9   │       │    │ 7 8 4 │ 6 9 1 │ 3 2 5 │
 │       │       │   4   │    │ 6 9 5 │ 2 8 3 │ 7 4 1 │
 ├───────┼───────┼───────┤    ├───────┼───────┼───────┤
 │     8 │       │       │    │ 1 7 8 │ 9 6 4 │ 5 3 2 │
 │     9 │       │   1   │    │ 5 2 9 │ 3 7 8 │ 4 1 6 │
 │       │ 5     │     8 │    │ 3 4 6 │ 5 1 2 │ 9 7 8 │
 └───────┴───────┴───────┘    └───────┴───────┴───────┘

Generating Sudokus

var generator = new Generator();

var puzzle = generator.Generate(51); // Will remove 51 cells, leaving a puzzle with 30 clues.

puzzle.DumpToConsole(1);

Output:

 ┌───────┬───────┬───────┐
 │   6   │     4 │   2 8 │
 │       │   8 9 │     6 │
 │ 9 5   │       │       │
 ├───────┼───────┼───────┤
 │     5 │       │       │
 │ 6   4 │       │       │
 │ 8     │ 4 2   │   7 3 │
 ├───────┼───────┼───────┤
 │     6 │       │     7 │
 │       │       │ 4 8   │
 │       │       │       │
 └───────┴───────┴───────┘