private static PuzzleGrid Solve(PuzzleGrid puzzle, out bool solved)
{
var anyChanges = false;
do
{
anyChanges = false;
var unsolvedCells = puzzle.Cells
.Where(c => !c.Solution.HasValue)
.ToArray();
if (!unsolvedCells.Any())
{
solved = true;
return(puzzle);
}
if (anyChanges |= unsolvedCells.TrySingleCandidateSolve())
{
Console.WriteLine("Single candidate.");
continue;
}
if (anyChanges |= unsolvedCells.TryUniqueCandidateSolve())
{
Console.WriteLine("Unique candidate.");
continue;
}
if (anyChanges |= puzzle.Boxes.TryCandidateLineElimination())
{
Console.WriteLine("Candidate line.");
continue;
}
if (anyChanges |= puzzle.AllUnits.TryNakedPairElimination())
{
Console.WriteLine("Naked pair.");
continue;
}
if (anyChanges |= puzzle.AllUnits.TryNakedTripleElimination())
{
Console.WriteLine("Naked triple.");
continue;
}
if (anyChanges |= puzzle.AllUnits.TryNakedQuadElimination())
{
Console.WriteLine("Naked quadruple.");
continue;
}
if (anyChanges |= puzzle.AllUnits.TryNakedQuintElimination())
{
Console.WriteLine("Naked quintuplet.");
continue;
}
if (anyChanges |= puzzle.TryDoublePairElimination())
{
Console.WriteLine("Double pair.");
continue;
}
if (anyChanges |= puzzle.TryClosedLoopCandidateElimination(loopScale: 2))
{
Console.WriteLine("X-Wing.");
continue;
}
if (anyChanges |= puzzle.TryClosedLoopCandidateElimination(loopScale: 3))
{
Console.WriteLine("Swordfish.");
continue;
}
if (anyChanges |= puzzle.TryClosedLoopCandidateElimination(loopScale: 4))
{
Console.WriteLine("Closed loop, scale 4.");
continue;
}
if (anyChanges |= puzzle.TryClosedLoopCandidateElimination(loopScale: 5))
{
Console.WriteLine("Closed loop, scale 5.");
continue;
}
//var mostSolvedCellIdx = unsolvedCells
// .OrderBy(c => c.Candidates.CountExcluding(IncorrectGuesses[c.Idx]))
// .First()
// .Idx;
//var clone = puzzle.DeepClone();
//var cell = clone.Cells[mostSolvedCellIdx];
//var nextGuess = cell.Candidates.FirstOrDefaultExcluding(IncorrectGuesses[mostSolvedCellIdx]);
//if(nextGuess == Candidates.None)
//{
// throw new InvalidOperationException($"No remaining guesses for cell {mostSolvedCellIdx}");
//}
//Console.WriteLine($"Guessing {nextGuess} on cell {cell.Idx}");
//cell.Solve(nextGuess);
//try
//{
// Solve(clone, out solved);
// if (solved)
// {
// return clone;
// }
// anyChanges = true;
//}
//catch (InvalidSolutionException)
//{
// Console.WriteLine("Incorrect guess.");
// IncorrectGuesses[mostSolvedCellIdx] |= nextGuess;
// solved = false;
// return clone;
//}
}while (anyChanges);
solved = false;
return(puzzle);
}
