internal int PopulateBestGuesses(Span <Guess> toPopulate)
{
int maxPossibleValues = MaxGuessCount + 1;
Objective?bestObjective = null;
foreach (Objective?objective in _graph.GetUnsatisfiedRequiredObjectivesWithConcretePossibilities())
{
if (!objective.AllUnknownPossibilitiesAreConcrete)
{
continue;
}
if (objective.AllUnknownPossibilitiesAreRequired)
{
Possibility possibility = (Possibility)objective
.GetUnknownDirectPossibilities().First();
toPopulate[0] = new Guess(possibility.Coordinate, possibility.Index);
return(1);
}
var numPossibilities = objective.CountUnknown;
if (numPossibilities < maxPossibleValues)
{
maxPossibleValues = numPossibilities;
bestObjective = objective;
}
}
Debug.Assert(
bestObjective is not null,
$"{nameof(bestObjective)} was still null at the end of {nameof(PopulateBestGuesses)}.");
return(_PopulateGuessesFromObjective(bestObjective, toPopulate));
}
private ExactCoverGraph(ExactCoverGraph other)
{
int length = other._possibilities.Length;
_possibilities = new Possibility[length][][];
for (int rowIndex = 0; rowIndex < length; ++rowIndex)
{
_possibilities[rowIndex] = new Possibility[length][];
}
_allPossibleValues = other.AllPossibleValues.ToArray();
ValuesToIndices = other.ValuesToIndices;
}
private ExactCoverGraph(IReadOnlyPuzzle puzzle)
{
int size = puzzle.Size;
_possibilities = new Possibility[size][][];
for (int rowIndex = 0; rowIndex < size; ++rowIndex)
{
_possibilities[rowIndex] = new Possibility[size][];
}
_allPossibleValues = puzzle.AllPossibleValuesSpan.ToArray();
var valuesToIndices = new Dictionary <int, int>(_allPossibleValues.Length);
for (int index = 0; index < _allPossibleValues.Length; index++)
{
valuesToIndices[_allPossibleValues[index]] = index;
}
ValuesToIndices = valuesToIndices;
}
