public void TestPuzzleValidity()
{
int dimension = 3;
List <int> cellValues = new List <int>();
// Test a row
for (int i = 0; i < dimension * dimension * dimension * dimension; ++i)
{
cellValues.Add(0);
}
SudokuPuzzle puzzle = new SudokuPuzzle(dimension, cellValues);
Assert.IsTrue(puzzle.IsValid());
// Test a column having the same value twice
for (int i = 0; i < dimension * dimension; ++i)
{
puzzle.Rows[0][i].RemoveAllExcept(i + 1);
}
Assert.IsTrue(puzzle.IsValid());
puzzle.Rows[dimension + 1][0].RemoveAllExcept(1);
Assert.IsFalse(puzzle.IsValid());
// Test a block having the same value twice
puzzle = new SudokuPuzzle(dimension, cellValues);
for (int i = 0; i < dimension * dimension; ++i)
{
puzzle.Rows[0][i].RemoveAllExcept(i + 1);
}
puzzle.Rows[1][1].RemoveAllExcept(1);
Assert.IsFalse(puzzle.IsValid());
// Test a row having the same value twice
puzzle = new SudokuPuzzle(dimension, cellValues);
for (int i = 0; i < dimension * dimension; ++i)
{
puzzle.Columns[0][i].RemoveAllExcept(i + 1);
}
Assert.IsTrue(puzzle.IsValid());
puzzle.Rows[0][1].RemoveAllExcept(1);
Assert.IsFalse(puzzle.IsValid());
}
/// <summary>
/// Solves the given <see cref="SudokuPuzzle"/>
/// </summary>
/// <param name="puzzle">The <see cref="SudokuPuzzle"/> being solved</param>
/// <returns>A list of <see cref="SudokuPuzzle"/>s that are solutions to the given <see cref="SudokuPuzzle"/></returns>
public List <SudokuPuzzle> Solve(SudokuPuzzle puzzle)
{
List <SudokuPuzzle> solutions = new List <SudokuPuzzle>();
Stack <SudokuPuzzle> puzzleStack = new Stack <SudokuPuzzle>();
puzzleStack.Push(puzzle.Clone());
while (puzzleStack.Count > 0)
{
try
{
SudokuPuzzle puzzleToSolve = puzzleStack.Pop();
if (puzzle.IsValid())
{
bool puzzleAdvanced = false;
do
{
puzzleAdvanced = false;
for (int i = 0; i < this.strategies.Count; ++i)
{
while (this.strategies[i].AdvancePuzzle(puzzleToSolve))
{
puzzleAdvanced = true;
}
}
}while (puzzleAdvanced);
if (puzzleToSolve.IsSolved() && puzzleToSolve.IsValid())
{
solutions.Add(puzzleToSolve);
if (solutions.Count > 1)
{
break;
}
}
else
{
foreach (SudokuPuzzle guess in this.Guess(puzzleToSolve))
{
puzzleStack.Push(guess);
}
}
}
}
catch (Exception)
{
}
}
return(solutions);
}
/// <summary>
/// Finds a <see cref="Cell"/> with the least possible values (other than solved <see cref="Cell"/>s),
/// and tries each possible puzzle using those values in that cell
/// </summary>
/// <param name="puzzle">The <see cref="SudokuPuzzle"/> being solved</param>
/// <returns>The puzzle solutions found from guessing</returns>
private List <SudokuPuzzle> Guess(SudokuPuzzle puzzle)
{
if (!puzzle.IsValid())
{
return(new List <SudokuPuzzle>());
}
Cell cellToGuessOn = null;
int x = -1;
int y = -1;
for (int i = 0; i < puzzle.Rows.Count; ++i)
{
for (int k = 0; k < puzzle.Rows[i].Count; ++k)
{
Cell cell = puzzle.Rows[i][k];
if (cell.Count > 1)
{
if (cellToGuessOn == null)
{
cellToGuessOn = cell;
x = i;
y = k;
}
else if (cellToGuessOn.Count > cell.Count)
{
cellToGuessOn = cell;
x = i;
y = k;
}
}
}
}
List <SudokuPuzzle> guesses = new List <SudokuPuzzle>();
if (cellToGuessOn != null)
{
foreach (int allowedValue in cellToGuessOn.AllowedValues.Keys)
{
SudokuPuzzle guess = puzzle.Clone();
guess.Rows[x][y].RemoveAllExcept(allowedValue);
guesses.Add(guess);
}
}
return(guesses);
}
