private bool IsValidMove(Puzzle puzzle, int r, int c, char value)
{
var row = puzzle.RowAt(r);
var col = puzzle.ColumnAt(c);
var box = puzzle.BoxAt(r, c);
return !(row.Any(cell => cell.Value == value) ||
col.Any(cell => cell.Value == value) ||
box.Any(cell => cell.Value == value));
}
public override bool SolveCell(Puzzle puzzle, int r, int c)
{
return FindLastOne(puzzle, r, c, puzzle.BoxAt(r, c)) ||
FindLastOne(puzzle, r, c, puzzle.ColumnAt(c)) ||
FindLastOne(puzzle, r, c, puzzle.RowAt(r));
}
