private static void SolveSudokuProblem()
{
var initialState =
new SudokuState(
new int[9, 9]
{
{ 0, 0, 5, 0, 3, 0, 0, 6, 2 },
{ 0, 3, 0, 8, 9, 0, 0, 0, 1 },
{ 0, 2, 9, 4, 0, 0, 0, 0, 0 },
{ 0, 0, 0, 2, 6, 0, 0, 0, 0 },
{ 8, 9, 3, 0, 0, 0, 0, 0, 0 },
{ 6, 0, 0, 0, 0, 0, 8, 5, 0 },
{ 3, 6, 8, 9, 0, 0, 0, 0, 0 },
{ 0, 0, 4, 0, 0, 0, 0, 9, 6 },
{ 0, 0, 0, 0, 4, 3, 0, 0, 0 }
});
var actionFunction = new SudokuActionFunction();
var resultFunction = new SudokuResultFunction();
var goalTest = new SudokuGoalTest();
var stepCost = new SudokuStepCost();
var searchAlgorithm = new GraphSearch <SudokuState, SudokuAction>();
SolveProblem(actionFunction, resultFunction, goalTest, stepCost, initialState, searchAlgorithm);
}
private void Solve(SudokuPuzzle puzzle, string input, string expected)
{
var state = SudokuState.Parse(input);
var solver = new SudokuSolver(puzzle);
var sw = Stopwatch.StartNew();
var actual = solver.Solve(state);
sw.Stop();
Console.WriteLine("Elapsed: {0:#,##0.#####} ms", sw.Elapsed.TotalMilliseconds);
Console.WriteLine(actual);
Assert.IsTrue(actual.IsSolved, "The puzzle is not solved.");
Assert.AreEqual(SudokuState.Parse(expected), actual);
}
public void Parse_3x3_ReturnSudokuState3x3()
{
var puzzle = SudokuState.Parse(@"
53.|.7.|...
6..|195|...
.98|...|.6.
---+---+---
8..|.6.|..3
4..|8.3|..1
7..|.2.|..6
---+---|---
.6.|...|28.
...|419|..5
...|.8.|.79" );
Assert.AreEqual(3, puzzle.Size);
}
/// <summary>Reduces hidden singles.</summary>
/// <remarks>
/// Very frequently, there is only one candidate for a given row, column or
/// sub square, but it is hidden among other candidates.
/// </remarks>
private ReduceResult ReduceHiddenSingles(ReduceResult result, SudokuState state)
{
if (SkipMethod(SudokuSolverMethods.HiddenSingles, result)) { return result; }
foreach (var region in Puzzle.Regions)
{
foreach (var singleValue in Puzzle.SingleValues)
{
var cnt = 0;
var found = -1;
foreach (var index in region)
{
var val = state[index];
if ((val & singleValue) != SudokuPuzzle.Invalid)
{
unchecked { cnt++; }
if (state.IsKnown(index))
{
found = -1;
break;
}
else if (cnt == 1)
{
found = index;
}
}
}
if (cnt == 1 && found != -1)
{
result |= state.AndMask(found, singleValue);
}
else if (cnt == 0)
{
return ReduceResult.Inconsistend;
}
}
}
return result;
}
/// <summary>Solves a Sudoku puzzle given the Sudoku state.</summary>
public SudokuState Solve(SudokuState sudokuState)
{
// As states are not immutable, create a copy.
var state = sudokuState.Copy();
var result = ReduceResult.Reduced;
while (result == ReduceResult.Reduced)
{
result = ReduceResult.None;
result |= ReduceSingles(result, state);
result |= ReduceHiddenSingles(result, state);
result |= ReduceLockedCandidates(result, state);
result |= ReduceNakedPairs(result, state);
result |= ReduceNakedTriples(result, state);
result |= ReduceNakedQuads(result, state);
}
if (result.HasFlag(ReduceResult.Inconsistend))
{
throw new InvalidPuzzleException();
}
return state;
}
/// <summary>Reduces singles.</summary>
/// <remarks>
/// Any cells which have only one candidate can safely be assigned that value.
///
/// It is very important whenever a value is assigned to a cell, that this
/// value is also excluded as a candidate from all other blank cells sharing
/// the same row, column and sub square.
/// </remarks>
private ReduceResult ReduceSingles(ReduceResult result, SudokuState state)
{
if (SkipMethod(SudokuSolverMethods.Singles, result)) { return result; }
result = ReduceResult.Reduced;
while (result == ReduceResult.Reduced)
{
result = ReduceResult.None;
for (var index1 = 0; index1 <= Puzzle.MaximumIndex; index1++)
{
if (state.IsKnown(index1))
{
foreach (var group in Puzzle.Lookup[index1])
{
foreach (var index0 in group)
{
if (index0 != index1)
{
result |= state.Exclude(index0, index1);
}
}
}
}
}
}
return result;
}
/// <summary>Reduces naked triples.</summary>
private ReduceResult ReduceNakedTriples(ReduceResult result, SudokuState state)
{
if (SkipMethod(SudokuSolverMethods.NakedTriples, result)) { return result; }
foreach (var singleValue in Puzzle.SingleValues)
{
foreach (var region in Puzzle.Regions)
{
var index0 = -1;
var index1 = -1;
var index2 = -1;
var match = singleValue;
foreach (var index in region)
{
var value = state[index];
if (!state.IsKnown(index) && (value & match) != SudokuPuzzle.Invalid)
{
match |= value;
/**/ if (index0 == -1) { index0 = index; }
else if (index1 == -1) { index1 = index; }
else if (index2 == -1) { index2 = index; }
else { index2 = -1; break; }
}
}
// We found 3 cells.
if (index2 != -1 && SudokuCell.Count(match) == 3)
{
foreach (var index in region)
{
if (index != index0 && index != index1 && index != index2)
{
result |= state.AndMask(index, ~match);
}
}
}
}
}
return result;
}
/// <summary>Reduces options that should be in the intersection.</summary>
private ReduceResult ReduceLockedCandidates(ReduceResult result, SudokuState state)
{
if (SkipMethod(SudokuSolverMethods.LockedCandidates, result)) { return result; }
foreach (var region in Puzzle.Regions)
{
foreach (var other in region.Intersected)
{
ulong combined = 0;
foreach (var index in region)
{
if (!other.Contains(index))
{
combined |= state[index];
}
}
// There are options that should be in the intersection.
if (combined != Puzzle.Unknown)
{
foreach (var index in other)
{
if (!region.Contains(index))
{
var val = state[index];
var nw = val & combined;
result |= state.AndMask(index, nw);
}
}
}
}
}
return result;
}
public SudokuSolver(SudokuState sudokuState, SudokuBlock sudokuBlock)
{
_sudokuState = sudokuState;
_sudokuBlock = sudokuBlock;
}