/// <summary>
/// For a given piece, generate all of the potential placements and add them
/// as rows to the model.
/// </summary>
/// <param name="dancer">the problem model</param>
/// <param name="piece">the piece we are trying to place</param>
/// <param name="width">the width of the board</param>
/// <param name="height">the height of the board</param>
/// <param name="flip">is the piece flipped over?</param>
/// <param name="row">a workspace the length of the each row in the table</param>
/// <param name="upperLeft">
/// is the piece constrained to the upper left of the board?
/// this is used on a single piece to eliminate most of the trivial
/// roations of the solution.
/// </param>
private static void GenerateRows(DancingLinks dancer, Pentomino.Piece piece, int
width, int height, bool flip, bool[] row, bool upperLeft)
{
// for each rotation
int[] rotations = piece.GetRotations();
for (int rotIndex = 0; rotIndex < rotations.Length; ++rotIndex)
{
// get the shape
bool[][] shape = piece.GetShape(flip, rotations[rotIndex]);
// find all of the valid offsets
for (int x = 0; x < width; ++x)
{
for (int y = 0; y < height; ++y)
{
if (y + shape.Length <= height && x + shape[0].Length <= width && (!upperLeft ||
(IsSide(x, shape[0].Length, width) && IsSide(y, shape.Length, height))))
{
// clear the columns related to the points on the board
for (int idx = 0; idx < width * height; ++idx)
{
row[idx] = false;
}
// mark the shape
for (int subY = 0; subY < shape.Length; ++subY)
{
for (int subX = 0; subX < shape[0].Length; ++subX)
{
row[(y + subY) * width + x + subX] = shape[subY][subX];
}
}
dancer.AddRow(row);
}
}
}
}
}
private DancingLinks <Sudoku.ColumnName> MakeModel()
{
DancingLinks <Sudoku.ColumnName> model = new DancingLinks <Sudoku.ColumnName>();
// create all of the columns constraints
for (int x = 0; x < size; ++x)
{
for (int num = 1; num <= size; ++num)
{
model.AddColumn(new Sudoku.ColumnConstraint(num, x));
}
}
// create all of the row constraints
for (int y = 0; y < size; ++y)
{
for (int num = 1; num <= size; ++num)
{
model.AddColumn(new Sudoku.RowConstraint(num, y));
}
}
// create the square constraints
for (int x_1 = 0; x_1 < squareYSize; ++x_1)
{
for (int y_1 = 0; y_1 < squareXSize; ++y_1)
{
for (int num = 1; num <= size; ++num)
{
model.AddColumn(new Sudoku.SquareConstraint(num, x_1, y_1));
}
}
}
// create the cell constraints
for (int x_2 = 0; x_2 < size; ++x_2)
{
for (int y_1 = 0; y_1 < size; ++y_1)
{
model.AddColumn(new Sudoku.CellConstraint(x_2, y_1));
}
}
bool[] rowValues = new bool[size * size * 4];
for (int x_3 = 0; x_3 < size; ++x_3)
{
for (int y_1 = 0; y_1 < size; ++y_1)
{
if (board[y_1][x_3] == -1)
{
// try each possible value in the cell
for (int num = 1; num <= size; ++num)
{
model.AddRow(GenerateRow(rowValues, x_3, y_1, num));
}
}
else
{
// put the given cell in place
model.AddRow(GenerateRow(rowValues, x_3, y_1, board[y_1][x_3]));
}
}
}
return(model);
}