/// <summary> <!-- {{{1 --> Get cells from house index
/// </summary>
/// <param name="idx"></param>
/// <returns></returns>
public IEnumerable <Cell> CellsFromHouse(SudokuHouseIndex idx)
{
idx.AssertWhenInvalid();
return(CellsFromRow(idx)
.Concat(CellsFromCol(idx))
.Concat(CellsFromBox(idx)));
}
/// <summary> <!-- {{{1 --> Throw exception when specified index is invalid.
/// </summary>
/// <param name="self"></param>
public static void AssertWhenInvalid(this SudokuHouseIndex self)
{
if (self.IsInvalid())
{
var msg = string.Format("Invalid house index: {0}", self.ToInt());
throw new ArgumentOutOfRangeException(msg);
}
}
/// <summary> <!-- {{{1 --> Convert house index to cell indexes in box.
/// </summary>
/// <param name="self"></param>
/// <returns></returns>
public static IEnumerable <SudokuCellIndex> ToCellsIndexInBox(this SudokuHouseIndex self)
{
// calculate Top Left index in target Box
var idx = self.ToInt();
int topleft = (27 * (idx / 3)) + (3 * (idx % 3));
return(Enumerable.Range(0, 3)
.SelectMany(y => Enumerable.Range(0, 3)
.Select(x => (SudokuCellIndex)(topleft + x + 9 * y))));
}
/// <summary> <!-- {{{1 --> Convert house index to cell indexes in column.
/// </summary>
/// <param name="self"></param>
/// <returns></returns>
public static IEnumerable <SudokuCellIndex> ToCellsIndexInCol(this SudokuHouseIndex self)
{
return(Enumerable.Range(0, 9)
.Select(x => (SudokuCellIndex)(9 * x + self.ToInt())));
}
/// <summary> <!-- {{{1 --> Convert house index to cell indexes in row.
/// </summary>
/// <param name="self"></param>
/// <returns></returns>
public static IEnumerable <SudokuCellIndex> ToCellsIndexInRow(this SudokuHouseIndex self)
{
return(SudokuCellIndexExtension.IndexList()
.Skip(self.ToInt() * 9).Take(9));
}
/// <summary> <!-- {{{1 --> Convert the house index to String
/// </summary>
/// <param name="self"></param>
/// <returns></returns>
public static string ToStr(this SudokuHouseIndex self)
{
return(self.ToInt().ToString());
}
/// <summary> <!-- {{{1 --> Convert the house index to Integer
/// </summary>
/// <param name="self"></param>
/// <returns></returns>
public static int ToInt(this SudokuHouseIndex self)
{
return((int)self);
}
/// <summary> <!-- {{{1 --> Return true if the index is invalid.
/// </summary>
/// <param name="self"></param>
/// <returns></returns>
public static bool IsInvalid(this SudokuHouseIndex self)
{
return((SudokuHouseIndex._1 > self) || (SudokuHouseIndex._9 < self));
}
/// <summary> <!-- {{{1 --> Get cells from box index
/// </summary>
/// <param name="idx"></param>
/// <returns></returns>
public IEnumerable <Cell> CellsFromBox(SudokuHouseIndex idx)
{
idx.AssertWhenInvalid();
return(idx.ToCellsIndexInBox().Select(x => this.board.ElementAt(x.ToInt())));
}
