private static IImmutableList<Tuple<int, int, int, bool>> BuildInternalRowsForGrid(Grid grid)
{
var rowsByCols =
from row in Rows
from col in Cols
let value = grid.ValueAt(row, col)
select BuildInternalRowsForCell(row, col, value);
return rowsByCols.SelectMany(cols => cols).ToImmutableList();
}
private static void Main()
{
// http://puzzles.telegraph.co.uk/site/search_puzzle_number?id=27744
var grid = new Grid(ImmutableList.Create(
"6 4 9 7 3",
" 3 6 ",
" 18",
" 18 9",
" 43 ",
"7 39 ",
" 7 ",
" 4 8 ",
"9 8 6 4 5"));
grid.Draw();
var internalRows = BuildInternalRowsForGrid(grid);
var dlxRows = BuildDlxRows(internalRows);
var solutions = new Dlx()
.Solve(dlxRows, d => d, r => r)
.Where(solution => VerifySolution(internalRows, solution))
.ToImmutableList();
Console.WriteLine();
if (solutions.Any())
{
Console.WriteLine($"First solution (of {solutions.Count}):");
Console.WriteLine();
DrawSolution(internalRows, solutions.First());
Console.WriteLine();
}
else
{
Console.WriteLine("No solutions found!");
}
}
