/// <summary>
/// Solves the grid in-place.
/// </summary>
/// <param name="grid">
/// The grid to solve. This grid will be modified to contain the solution to
/// the sudoku puzzle, if it exists.
/// </param>
/// <returns>
/// If the puzzle can be unambiguously solved, Solve() will return true.
/// If the puzzle cannot be solved or has more than one solution,
/// this will return false.
/// </returns>
public bool Solve(Grid grid)
{
int numSolutions = 0;
Grid solutionGrid = grid.Copy();
if (FindErrors(grid).Count > 0)
{
// fail fast!
return(false);
}
// this bit here GREATLY simplifies DepthFirstSearch.
// Using exceptions and a lambda to terminate after two
// solutions frees DepthFirstSearch from worrying about
// all that logic at the cost of a closure and tricky
// exception handling.
// all of this is to avoid C#'s lack of generators, buh
try {
DepthFirstSearch(grid, () => {
// this lambda gets run on each solution
numSolutions++;
solutionGrid = grid.Copy();
if (numSolutions > 1)
{
throw new StopIterationException();
}
});
}
catch (StopIterationException e) { }
// (just pretend that empty catch block is a generator)
grid.CopyFrom(solutionGrid);
return(numSolutions == 1);
}
/// <summary>
/// When the File -> Save Game Unsolved menu item is chosen
/// </summary>
private void FileSaveGameUnsolvedClick(object sender, EventArgs e)
{
Grid unsolvedGrid = grid.Copy();
unsolvedGrid.ForEachSquare((row, col, val) =>
{
if (unsolvedGrid.IsEditable(row, col))
{
unsolvedGrid.Clear(row, col);
}
});
GameManager.SaveGame(unsolvedGrid);
}
/// <summary>
/// When the player transitions from "edit grid" mode to "play this game" mode
/// </summary>
internal static void PlayThisPuzzle(Grid oldGrid, Form form)
{
// Set all the squares as non-editable
Grid grid = oldGrid.Copy();
grid.ForEachSquare((row, col, val) =>
{
if (val != 0)
{
grid.SetEditable(false, row, col);
}
});
// Tries to solve the grid. If the grid has no unique solution, warn first.
Grid copyGrid = grid.Copy(); // yes another copy; the solver will mess with this one.
bool result = (new Solver().Solve(copyGrid));
if (result)
{
SaveGame(grid);
form.Hide();
GameForm gform = new GameForm(grid, true);
gform.ShowDialog();
form.Close();
}
else
{
if (MessageBox.Show(copyGrid.IsFull()? "This puzzle can be solved in more than one way. Play anyway?" : "This puzzle cannot be solved. Play anyway?", "Unsolvable Puzzle", MessageBoxButtons.YesNo) == DialogResult.Yes)
{
SaveGame(grid);
form.Hide();
GameForm gform = new GameForm(grid, true);
gform.ShowDialog();
form.Close();
}
}
}
/// <summary>
/// Creates a new form for playing the game
/// </summary>
/// <param name="grid">The grid to start with</param>
/// <param name="playingMode">If true: We're "playing" the game. If false: We're "editing" the game.</param>
public GameForm(Grid grid, bool playingMode)
{
InitializeComponent();
this.grid = grid;
this.isPlaying = playingMode;
hintBarText.Text = "";
if (isPlaying)
{
solveButton.Text = "&Solve";
}
else
{
solveButton.Text = "&Enter Puzzle";
}
// make the grid control and put it somewhere
this.gcontrol = new SudokuGridControl(grid);
this.gridPanel.Controls.Add(gcontrol);
gcontrol.Dock = DockStyle.Fill;
// When the cell is cleared, mark/unmark errors and hints
gcontrol.CellClear += (int row, int col) =>
{
nagAboutErrors = true;
nagAboutWonGame = true;
RecalculateErrors();
RecalculateHints(row, col);
ShowOrHideHintBar();
};
// When the cell's value is changed, mark/unmark errors and hints
gcontrol.CellChange += (int row, int col) =>
{
MaybeTryGameOver();
RecalculateErrors();
RecalculateHints(row, col);
ShowOrHideHintBar();
};
// When the user selects a different cell, mark/unmark errors and hints
gcontrol.CellFocused += (int row, int col) =>
{
ShowOrHideHintBar();
if (isPlaying)
{
RecalculateHints(row, col);
}
};
// Add a drop-down context menu to each textbox
gcontrol.ForEachTextBox((TextBox tbox, int row, int col) =>
{
tbox.ContextMenu = new ContextMenu();
if (isPlaying)
{
// The context menu should only appear when in "Playing" mode
tbox.ContextMenu.MenuItems.Add(new MenuItem("Show &Hints", (s, e) =>
{
hintBarText.Show();
// the hints bar will disappear on next call to ShowOrHideHints()
}));
tbox.ContextMenu.MenuItems.Add(new MenuItem("&Solve This Square", (s, e) =>
{
// solve the grid and copy the value
if (grid.IsEditable(row, col))
{
Grid solvedGrid = grid.Copy();
solver.Solve(solvedGrid);
if (!solvedGrid.IsFull())
{
MessageBox.Show("This square cannot be solved because there are errors in your puzzle. Please erase some of your work and try again.");
}
else
{
grid.Set(solvedGrid.Get(row, col), true, row, col);
}
gcontrol.UpdateGridView();
RecalculateErrors();
}
}));
}
});
// initial setup: start the timer and optionally show errors.
gameTimerTick(this, new EventArgs());
RecalculateErrors();
ShowOrHideHintBar();
}
/// <summary>
/// Overwrite this grid's elements with elements from another grid.
/// The two grids will share nothing.
/// </summary>
public void CopyFrom(Grid other)
{
this.elts = other.Copy().elts;
}
/// <summary>
/// Overwrite this grid's elements with elements from another grid.
/// The two grids will share nothing.
/// </summary>
public void CopyFrom(Grid other)
{
this.elts = other.Copy().elts;
}
/// <summary>
/// Generates a grid with the given difficulty level.
/// </summary>
public Grid Generate(DifficultyLevel difficulty)
{
// Generates stuff
// 1. Randomnly fill in the top and left part of the grid.
// 2. Try to solve it
// 3. Until we have enough blanks:
// remove some blanks
// if it isn't uniquely solvable, add those two blanks again.
Grid grid = GenerateBlankGrid();
Grid result;
// Top row
List <int> row = Enumerable.Range(1, 9).OrderBy((i) => rand.Next()).ToList();
for (int i = 0; i < 9; i++)
{
grid.Set(row[i], false, i, 0);
}
// Top column
row = Enumerable.Range(1, 9).OrderBy((i) => rand.Next()).ToList();
row.Remove(grid.Get(0, 0));
for (int i = 0; i < 8; i++)
{
grid.Set(row[i], false, 0, i + 1);
}
if (solver.FindErrors(grid).Count > 0)
{
// This is not enough to guarantee correctness.
// If we get an invalid grid, try try again!
result = Generate(difficulty);
}
else
{
solver.Solve(grid);
// How many blanks do we need?
int targetBlanks = 0;
switch (difficulty)
{
case DifficultyLevel.Easy:
targetBlanks = 30;
break;
case DifficultyLevel.Medium:
targetBlanks = 45;
break;
case DifficultyLevel.Hard:
targetBlanks = 50;
break;
}
// Remove squares until we have the right number of blanks.
int tries = 0;
while (tries < 100 && CountBlank(grid) < targetBlanks)
{
Grid saveCopy = grid.Copy();
// Solving is expensive. Blanking squares is easy!
// When the grid is mostly full, you can blank squares
// in relative safety without generating a non-unique
// puzzle. When the puzzle gets more sparse, you
// need to be more careful.
// That's what we're doing here. Quick optimization.
for (int i = 0; i < (targetBlanks - CountBlank(grid)) / 2 + 1; i++)
{
MaybeRandomBlank(grid);
}
if (!solver.Solve(grid.Copy()))
{
// it failed
grid = saveCopy;
}
tries++;
}
//Console.WriteLine("Generated puzzle in " + tries + " tries with "+CountBlank(grid)+" blanks");
// Finally, set every square to be not editable
grid.ForEachSquare((r, c, val) =>
{
if (val != 0)
{
grid.SetEditable(false, r, c);
}
});
result = grid;
}
return(result);
}
/// <summary>
/// Solves the grid in-place.
/// </summary>
/// <param name="grid">
/// The grid to solve. This grid will be modified to contain the solution to
/// the sudoku puzzle, if it exists.
/// </param>
/// <returns>
/// If the puzzle can be unambiguously solved, Solve() will return true.
/// If the puzzle cannot be solved or has more than one solution,
/// this will return false.
/// </returns>
public bool Solve(Grid grid)
{
int numSolutions = 0;
Grid solutionGrid = grid.Copy();
if (FindErrors(grid).Count > 0)
{
// fail fast!
return false;
}
// this bit here GREATLY simplifies DepthFirstSearch.
// Using exceptions and a lambda to terminate after two
// solutions frees DepthFirstSearch from worrying about
// all that logic at the cost of a closure and tricky
// exception handling.
// all of this is to avoid C#'s lack of generators, buh
try {
DepthFirstSearch(grid, () => {
// this lambda gets run on each solution
numSolutions++;
solutionGrid = grid.Copy();
if (numSolutions > 1) {
throw new StopIterationException();
}
});
}
catch (StopIterationException e) { }
// (just pretend that empty catch block is a generator)
grid.CopyFrom(solutionGrid);
return numSolutions == 1;
}
/// <summary>
/// When the player transitions from "edit grid" mode to "play this game" mode
/// </summary>
internal static void PlayThisPuzzle(Grid oldGrid, Form form)
{
// Set all the squares as non-editable
Grid grid = oldGrid.Copy();
grid.ForEachSquare((row, col, val) =>
{
if (val != 0)
{
grid.SetEditable(false, row, col);
}
});
// Tries to solve the grid. If the grid has no unique solution, warn first.
Grid copyGrid = grid.Copy(); // yes another copy; the solver will mess with this one.
bool result = (new Solver().Solve(copyGrid));
if (result)
{
SaveGame(grid);
form.Hide();
GameForm gform = new GameForm(grid, true);
gform.ShowDialog();
form.Close();
}
else
{
if (MessageBox.Show(copyGrid.IsFull()? "This puzzle can be solved in more than one way. Play anyway?" : "This puzzle cannot be solved. Play anyway?", "Unsolvable Puzzle", MessageBoxButtons.YesNo) == DialogResult.Yes)
{
SaveGame(grid);
form.Hide();
GameForm gform = new GameForm(grid, true);
gform.ShowDialog();
form.Close();
}
}
}
/// <summary>
/// Creates a new form for playing the game
/// </summary>
/// <param name="grid">The grid to start with</param>
/// <param name="playingMode">If true: We're "playing" the game. If false: We're "editing" the game.</param>
public GameForm(Grid grid, bool playingMode)
{
InitializeComponent();
this.grid = grid;
this.isPlaying = playingMode;
hintBarText.Text = "";
if (isPlaying)
{
solveButton.Text = "&Solve";
}
else
{
solveButton.Text = "&Enter Puzzle";
}
// make the grid control and put it somewhere
this.gcontrol = new SudokuGridControl(grid);
this.gridPanel.Controls.Add(gcontrol);
gcontrol.Dock = DockStyle.Fill;
// When the cell is cleared, mark/unmark errors and hints
gcontrol.CellClear += (int row, int col) =>
{
nagAboutErrors = true;
nagAboutWonGame = true;
RecalculateErrors();
RecalculateHints(row, col);
ShowOrHideHintBar();
};
// When the cell's value is changed, mark/unmark errors and hints
gcontrol.CellChange += (int row, int col) =>
{
MaybeTryGameOver();
RecalculateErrors();
RecalculateHints(row, col);
ShowOrHideHintBar();
};
// When the user selects a different cell, mark/unmark errors and hints
gcontrol.CellFocused += (int row, int col) =>
{
ShowOrHideHintBar();
if (isPlaying)
{
RecalculateHints(row, col);
}
};
// Add a drop-down context menu to each textbox
gcontrol.ForEachTextBox((TextBox tbox, int row, int col) =>
{
tbox.ContextMenu = new ContextMenu();
if (isPlaying)
{
// The context menu should only appear when in "Playing" mode
tbox.ContextMenu.MenuItems.Add(new MenuItem("Show &Hints", (s, e) =>
{
hintBarText.Show();
// the hints bar will disappear on next call to ShowOrHideHints()
}));
tbox.ContextMenu.MenuItems.Add(new MenuItem("&Solve This Square", (s, e) =>
{
// solve the grid and copy the value
if (grid.IsEditable(row, col))
{
Grid solvedGrid = grid.Copy();
solver.Solve(solvedGrid);
if (!solvedGrid.IsFull())
{
MessageBox.Show("This square cannot be solved because there are errors in your puzzle. Please erase some of your work and try again.");
}
else
{
grid.Set(solvedGrid.Get(row, col), true, row, col);
}
gcontrol.UpdateGridView();
RecalculateErrors();
}
}));
}
});
// initial setup: start the timer and optionally show errors.
gameTimerTick(this, new EventArgs());
RecalculateErrors();
ShowOrHideHintBar();
}