static List <Node <bool> > DancingLinks(TorodialDoubleLinkList <bool> list)
{
List <Node <bool> > solutions = new List <Node <bool> >();
ColumnNode <bool> column = list.H;
return(Search(list, column, solutions));
}
static List <Node <bool> > Search(TorodialDoubleLinkList <bool> list, ColumnNode <bool> column, List <Node <bool> > solutions)
{
if (list.H.Right == list.H)
{
foreach (Node <bool> result in solutions)
{
Console.Write(result.ColumnNode.ID + "," + result.Index + " ");
}
Console.WriteLine();
return(solutions);
}
else
{
column = getNextColumn(list);
Cover(column);
Node <bool> rowNode = column;
while (rowNode.Down != column)
{
rowNode = rowNode.Down;
solutions.Add(rowNode);
Node <bool> rightNode = rowNode;
while (rightNode.Right != rowNode)
{
rightNode = rightNode.Right;
Cover(rightNode);
}
List <Node <bool> > result = Search(list, column, solutions);
if (result != null)
{
return(result);
}
solutions.Remove(rowNode);
column = rowNode.ColumnNode;
Node <bool> leftNode = rowNode;
while (leftNode.Left != rowNode)
{
leftNode = leftNode.Left;
Uncover(leftNode);
}
}
Uncover(column);
}
return(null);
}
static ColumnNode <bool> getNextColumn(TorodialDoubleLinkList <bool> list)
{
ColumnNode <bool> node = list.H;
ColumnNode <bool> chosenNode = null;
while (node.Right != list.H)
{
node = (ColumnNode <bool>)node.Right;
if (chosenNode == null || node.Size < chosenNode.Size)
{
chosenNode = node;
}
}
return(chosenNode);
}
