private ImmutableSudokuGrid EmptyGridForSimpleSolve(ImmutableSudokuGrid inputGrid, SudokuSolver solver)
{
ImmutableSudokuGrid grid = inputGrid;
while (true)
{
bool hasSquareBeenRemoved = false;
List <SquareCoordinate> filledSquareList = grid.FindAllFilledSquares();
foreach (SquareCoordinate square in filledSquareList)
{
ImmutableSudokuGrid gridWithoutSquare = grid.WithoutSquare(square);
int numberOfOptions = solver.DetermineValidOptionsForSquare(square, gridWithoutSquare).Count;
if (numberOfOptions == 1)
{
grid = gridWithoutSquare;
hasSquareBeenRemoved = true;
}
}
if (!hasSquareBeenRemoved)
{
return(grid);
}
}
}
private ImmutableSudokuGrid EmptyGridForSimpleSolve(ImmutableSudokuGrid inputGrid, SudokuSolver solver)
{
ImmutableSudokuGrid grid = inputGrid;
while (true)
{
bool hasSquareBeenRemoved = false;
List<SquareCoordinate> filledSquareList = grid.FindAllFilledSquares();
foreach (SquareCoordinate square in filledSquareList)
{
ImmutableSudokuGrid gridWithoutSquare = grid.WithoutSquare(square);
int numberOfOptions = solver.DetermineValidOptionsForSquare(square, gridWithoutSquare).Count;
if (numberOfOptions == 1)
{
grid = gridWithoutSquare;
hasSquareBeenRemoved = true;
}
}
if (!hasSquareBeenRemoved)
{
return grid;
}
}
}
public void TryToSolveValidSudoku_CheckSolveReturnsCompletedGrid()
{
ImmutableSudokuGrid grid = new ImmutableSudokuGrid(CreateSudokuArray());
var returnFromSolve = sudokuSolver.Solve(grid);
var numberEmptySquares = returnFromSolve.FindAllEmptySquares().Count;
Assert.IsNotNull(grid);
Assert.AreEqual(numberEmptySquares, 0);
}
private ImmutableSudokuGrid Solve(ImmutableSudokuGrid grid, SudokuSolver simpleSolver, bool isRandomSolve, int disallowedValue, int disallowedRow, int disallowedColumn)
{
SudokuGrid mutableGrid = grid.MakeMutableCopy();
bool isGridValid = simpleSolver.TryAndSolveOnce(mutableGrid);
grid = new ImmutableSudokuGrid(mutableGrid.Elements);
if (!isGridValid)
{
return(null);
}
var emptySquareList = grid.FindAllEmptySquares();
if (emptySquareList.Count == 0)
{
return(grid);
}
SquareCoordinate emptySquareToFill = emptySquareList[0];
if (isRandomSolve)
{
var randomEmptySquare = new Random().Next(emptySquareList.Count - 1);
emptySquareToFill = emptySquareList[randomEmptySquare];
}
var validOptions = simpleSolver.DetermineValidOptionsForSquare(emptySquareToFill, grid);
if (emptySquareToFill.Row == disallowedRow && emptySquareToFill.Column == disallowedColumn && disallowedValue != 0)
{
validOptions.Remove(disallowedValue);
}
for (int i = 0; i < validOptions.Count; i++)
{
ImmutableSudokuGrid solvedGrid = Solve(grid.WithExtraSquare(emptySquareToFill, validOptions[i]), isRandomSolve);
if (solvedGrid != null)
{
return(solvedGrid);
}
}
return(null);
}
private ImmutableSudokuGrid Solve(ImmutableSudokuGrid grid, SudokuSolver simpleSolver, bool isRandomSolve, int disallowedValue, int disallowedRow, int disallowedColumn)
{
SudokuGrid mutableGrid = grid.MakeMutableCopy();
bool isGridValid = simpleSolver.TryAndSolveOnce(mutableGrid);
grid = new ImmutableSudokuGrid(mutableGrid.Elements);
if (!isGridValid)
{
return null;
}
var emptySquareList = grid.FindAllEmptySquares();
if (emptySquareList.Count == 0)
{
return grid;
}
SquareCoordinate emptySquareToFill = emptySquareList[0];
if (isRandomSolve)
{
var randomEmptySquare = new Random().Next(emptySquareList.Count - 1);
emptySquareToFill = emptySquareList[randomEmptySquare];
}
var validOptions = simpleSolver.DetermineValidOptionsForSquare(emptySquareToFill, grid);
if (emptySquareToFill.Row == disallowedRow && emptySquareToFill.Column == disallowedColumn && disallowedValue != 0)
{
validOptions.Remove(disallowedValue);
}
for (int i = 0; i < validOptions.Count; i++)
{
ImmutableSudokuGrid solvedGrid = Solve(grid.WithExtraSquare(emptySquareToFill, validOptions[i]), isRandomSolve);
if (solvedGrid != null)
{
return solvedGrid;
}
}
return null;
}
private ImmutableSudokuGrid EmptyGridForHardSolve(ImmutableSudokuGrid inputGrid, HarderSudokuSolver solver)
{
ImmutableSudokuGrid grid = EmptyGridForSimpleSolve(inputGrid);
var listOfFilledSquares = grid.FindAllFilledSquares();
for (int i = 0; i < listOfFilledSquares.Count; i++)
{
var square = listOfFilledSquares[i];
bool isNotUniqueValue = solver.CanBeSolvedWithDifferentValueInSquare(grid, square, grid.Elements[square.Row, square.Column]);
if (!isNotUniqueValue)
{
grid = grid.WithoutSquare(square);
return EmptyGridForHardSolve(grid);
}
}
return grid;
}
private ImmutableSudokuGrid EmptyGridForHardSolve(ImmutableSudokuGrid inputGrid, HarderSudokuSolver solver)
{
ImmutableSudokuGrid grid = EmptyGridForSimpleSolve(inputGrid);
var listOfFilledSquares = grid.FindAllFilledSquares();
for (int i = 0; i < listOfFilledSquares.Count; i++)
{
var square = listOfFilledSquares[i];
bool isNotUniqueValue = solver.CanBeSolvedWithDifferentValueInSquare(grid, square, grid.Elements[square.Row, square.Column]);
if (!isNotUniqueValue)
{
grid = grid.WithoutSquare(square);
return(EmptyGridForHardSolve(grid));
}
}
return(grid);
}
public void DetermineValidEntriesWorksCorrectly()
{
var grid = new ImmutableSudokuGrid(CreateNewMostlyEmptyArray());
var validOptionsFor00 = sudokuSolver.DetermineValidOptionsForSquare(new SquareCoordinate(0, 0), grid);
var validOptionsFor14 = sudokuSolver.DetermineValidOptionsForSquare(new SquareCoordinate(1, 4), grid);
Assert.AreEqual(validOptionsFor00.Count, 6);
for (int i = 4; i <= 9; i++)
{
Assert.IsTrue(validOptionsFor00.Contains(i));
}
Assert.AreEqual(validOptionsFor14.Count, 7);
for (int i = 1; i <= 9; i++)
{
if (i != 3 && i != 4)
{
Assert.IsTrue(validOptionsFor14.Contains(i));
}
}
}
static void Main(string[] args)
{
Console.WriteLine("Do you want me to try and solve an Easy Sudoku (type 1) or a Very Hard Sudoku (type 2)?");
string difficulty = Console.ReadLine();
if (difficulty == "1") { difficulty = "Easy" ; }
else if (difficulty == "2") { difficulty = "VeryHard"; }
else
{
Console.WriteLine("Stop being difficult. I'm going to solve an easy one then...");
difficulty = "Easy";
}
ImmutableSudokuGrid grid = new ImmutableSudokuGrid(@"..\..\..\" + difficulty + @"Sudoku.txt");
if (grid.Elements == null)
{
Console.WriteLine("Error, cannot read grid from file.");
return;
}
HarderSudokuSolver sudokuSolver = new HarderSudokuSolver();
sudokuSolver.Solve(grid).PrintGrid();
}
private ImmutableSudokuGrid CreateFilledGrid(HarderSudokuSolver solver)
{
ImmutableSudokuGrid sudokuGrid = new ImmutableSudokuGrid();
return solver.Solve(sudokuGrid, true);
}
public ImmutableSudokuGrid EmptyGridForSimpleSolve(ImmutableSudokuGrid grid)
{
return EmptyGridForSimpleSolve(grid, new SudokuSolver());
}
public ImmutableSudokuGrid EmptyGridForHardSolve(ImmutableSudokuGrid grid)
{
return EmptyGridForHardSolve(grid, new HarderSudokuSolver());
}
public void InitializeTest()
{
sudokuGrid = new ImmutableSudokuGrid(@"..\..\..\VeryHardSudoku.txt");
}
public ImmutableSudokuGrid Solve(ImmutableSudokuGrid grid, bool isRandomSolve = false, int disallowedValue = 0, int disallowedRow = -1, int disallowedColumn = -1)
{
return(Solve(grid, new SudokuSolver(), isRandomSolve, disallowedValue, disallowedRow, disallowedColumn));
}
public bool CanBeSolvedWithDifferentValueInSquare(ImmutableSudokuGrid grid, SquareCoordinate square, int disallowedValue)
{
ImmutableSudokuGrid differentValuedGrid = Solve(grid, disallowedValue: disallowedValue, disallowedRow: square.Row, disallowedColumn: square.Column);
return(differentValuedGrid == null ? false : true);
}
private ImmutableSudokuGrid CreateFilledGrid(HarderSudokuSolver solver)
{
ImmutableSudokuGrid sudokuGrid = new ImmutableSudokuGrid();
return(solver.Solve(sudokuGrid, true));
}
public bool CanBeSolvedWithDifferentValueInSquare(ImmutableSudokuGrid grid, SquareCoordinate square, int disallowedValue)
{
ImmutableSudokuGrid differentValuedGrid = Solve(grid, disallowedValue: disallowedValue, disallowedRow: square.Row, disallowedColumn : square.Column);
return differentValuedGrid == null ? false : true;
}
public void TryToSolveInvalidSudoku_CheckSolveReturnsNull()
{
ImmutableSudokuGrid grid = new ImmutableSudokuGrid(CreateInvalidSudokuArray());
var returnFromSolve = sudokuSolver.Solve(grid);
Assert.IsNull(returnFromSolve);
}
public ImmutableSudokuGrid EmptyGridForSimpleSolve(ImmutableSudokuGrid grid)
{
return(EmptyGridForSimpleSolve(grid, new SudokuSolver()));
}
public ImmutableSudokuGrid EmptyGridForHardSolve(ImmutableSudokuGrid grid)
{
return(EmptyGridForHardSolve(grid, new HarderSudokuSolver()));
}
public ImmutableSudokuGrid Solve(ImmutableSudokuGrid grid, bool isRandomSolve = false, int disallowedValue = 0, int disallowedRow = -1, int disallowedColumn = -1)
{
return Solve(grid, new SudokuSolver(), isRandomSolve, disallowedValue, disallowedRow, disallowedColumn);
}