private bool Update(SudokuGrid sudokuGrid)
{
bool somethingUpdated = false;
for (int i = 0; i < possible.Count; i++)
{
for (int j = 0; j < possible[i].Count; j++)
{
if (possible[i][j] != null)
{
if (possible[i][j].Count == 1)
{
somethingUpdated = true;
sudokuGrid[i, j] = possible[i][j][0];
sudokuGrid.EmptyFields--;
if (sudokuGrid.EmptyFields == 0)
{
solved = true;
return(true);
}
return(true);
}
}
}
}
return(somethingUpdated);
}
public SudokuSolver(SudokuGrid sudokuGrid)
{
possible = new List <List <List <int> > >();
for (int i = 0; i < sudokuGrid.Size; i++)
{
possible.Add(new());
}
}
public static List <int> CheckPossibleValues(SudokuGrid sudokuGrid, int row, int col)
{
var region = sudokuGrid.Get3x3Region(row, col);
List <int> possibleValues = GetPossibleValues(new() { 1, 2, 3, 4, 5, 6, 7, 8, 9 }, region);
possibleValues = GetPossibleValues(possibleValues, sudokuGrid.GetCol(col));
possibleValues = GetPossibleValues(possibleValues, sudokuGrid.GetRow(row));
return(possibleValues);
}
internal SudokuGrid Solve(SudokuGrid sudokuGrid)
{
if (!sudokuGrid.IsInDefaultForm)
{
throw new NotImplementedException("Cannot solve sudoku that is not in regular 9x9 form.");
}
var res = SolveDefaultForm(sudokuGrid);
solved = res.EmptyFields == 0;
return(res);
}
public SudokuGrid SolveDefaultForm(SudokuGrid sudokuGrid)
{
CreatePossibleList(sudokuGrid);
while (!solved)
{
if (sudokuGrid.EmptyFields == 0)
{
return(sudokuGrid);
}
if (!Update(sudokuGrid))
{
Tuple <int, int> minimal = GetMinOptions(possible);
if (minimal.Item1 == -1 || minimal.Item2 == -1)
{
return(sudokuGrid);
}
for (int k = 0; k < possible[minimal.Item1][minimal.Item2].Count; k++)
{
Sudoku s = new(sudokuGrid.Copy());
s.SudokuGrid.SetValue(minimal.Item1, minimal.Item2, possible[minimal.Item1][minimal.Item2][k]);
var temp = s.Solve();
if (s.SudokuSolver.solved)
{
return(temp);
}
else
{
continue;
}
}
return(sudokuGrid);
}
if (solved)
{
return(sudokuGrid);
}
CreatePossibleList(sudokuGrid);
}
return(sudokuGrid);
}
private void CreatePossibleList(SudokuGrid sudokuGrid)
{
possible = new List <List <List <int> > >();
for (int i = 0; i < sudokuGrid.Size; i++)
{
possible.Add(new());
}
for (int i = 0; i < sudokuGrid.Size; i++)
{
for (int j = 0; j < sudokuGrid.Size; j++)
{
if (sudokuGrid[i, j] == null)
{
this.possible[i].Add(CheckPossibleValues(sudokuGrid, i, j));
}
else
{
this.possible[i].Add(null);
}
}
}
}