private bool Attempt(Crossword crossword, CrosswordCell cell, IDictionary<CrosswordCell, List<char>> unresolvedCells)
{
var characters = unresolvedCells[cell];
var questions = crossword.GetQuestionsForCell(cell).ToArray();
foreach (var character in characters)
{
crossword.ApplyCharacter(cell, character);
if (!CheckQuestions(crossword, questions))
{
continue;
}
if (crossword.GetCells().All(c => crossword.GetCellCharacter(c) != 0))
{
return true;
}
foreach (var affectedCell in crossword.GetQuestionsForCell(cell).SelectMany(crossword.GetCellsForQuestion).Where(c => crossword.GetCellCharacter(c) == 0))
{
if (Attempt(crossword, affectedCell, unresolvedCells))
{
return true;
}
}
}
crossword.ApplyCharacter(cell, '\0');
return false;
}
public override IEnumerable<CrosswordQuestion> GetQuestionsForCell(CrosswordCell cell)
{
yield return _horizontalQuestions[cell.RowIndex];
yield return _verticalQuestions[cell.ColumnIndex];
}
public override char GetCellCharacter(CrosswordCell cell)
{
return _field[cell.RowIndex, cell.ColumnIndex];
}
public override void ApplyCharacter(CrosswordCell cell, char c)
{
_field[cell.RowIndex, cell.ColumnIndex] = c;
}
public abstract void ApplyCharacter(CrosswordCell cell, char c);
public abstract IEnumerable<CrosswordQuestion> GetQuestionsForCell(CrosswordCell cell);
public abstract char GetCellCharacter(CrosswordCell cell);