private static Grid Solve(SamplePuzzle samplePuzzle)
{
var rooms = samplePuzzle.Rooms;
var initialValues = samplePuzzle.InitialValues;
var numRows = rooms.SelectMany(r => r.Cells).Max(c => c.Row) + 1;
var numCols = rooms.SelectMany(r => r.Cells).Max(c => c.Col) + 1;
var maxValue = rooms.Max(r => r.Cells.Count);
var internalRows1 = rooms.SelectMany(room => BuildInternalRowsForRoom(rooms, initialValues, room));
var internalRows2 = initialValues.Select(t => BuildInternalRow(rooms, t.Item1, t.Item2, true));
var internalRows = internalRows1.Concat(internalRows2).ToImmutableList();
var dlxRows = BuildDlxRows(rooms, numRows, numCols, maxValue, internalRows);
var numRowColPrimaryColumns = numRows * numCols;
var numCellWithinRoomPrimaryColumns = rooms.Sum(r => r.Cells.Count);
var numPrimaryColumns = numRowColPrimaryColumns + numCellWithinRoomPrimaryColumns;
var dlx = new Dlx();
var solutions = dlx.Solve(dlxRows, d => d, r => r, numPrimaryColumns).ToList();
Console.WriteLine($"Number of solutions found: {solutions.Count}");
var firstSolution = solutions.FirstOrDefault();
if (firstSolution == null) return null;
var subsetOfInternalRows = firstSolution.RowIndexes.Select(idx => internalRows[idx]).ToImmutableList();
var orderedSubsetOfInternalRows = subsetOfInternalRows.OrderBy(t => t.Item1.Row).ThenBy(t => t.Item1.Col);
var rowStrings = Enumerable.Range(0, numRows).Select(row => string.Join("", orderedSubsetOfInternalRows.Skip(row * numCols).Take(numRows).Select(t => t.Item2)));
var grid = new Grid(rowStrings.ToImmutableList());
return grid;
}
private static Grid SamplePuzzleToGrid(SamplePuzzle samplePuzzle)
{
var rooms = samplePuzzle.Rooms;
var initialValues = samplePuzzle.InitialValues;
var numRows = rooms.SelectMany(r => r.Cells).Max(c => c.Row) + 1;
var numCols = rooms.SelectMany(r => r.Cells).Max(c => c.Col) + 1;
var rows = Enumerable.Range(0, numRows).Select(_ => new string(' ', numCols)).ToList();
foreach (var initialValue in initialValues)
{
var row = initialValue.Item1.Row;
var col = initialValue.Item1.Col;
var value = initialValue.Item2;
var s = rows[row];
var cs = s.ToCharArray();
cs[col] = Convert.ToChar('0' + value);
rows[row] = new string(cs);
}
return new Grid(rows.ToImmutableList());
}
