/// <summary>Find a solution to the problem.</summary>
/// <param name="partial">
/// a temporary datastructure to keep the current partial
/// answer in
/// </param>
/// <param name="output">the acceptor for the results that are found</param>
/// <returns>the number of solutions found</returns>
private int Search(IList <DancingLinks.Node <ColumnName> > partial, DancingLinks.SolutionAcceptor
<ColumnName> output)
{
int results = 0;
if (head.right == head)
{
IList <IList <ColumnName> > result = new AList <IList <ColumnName> >(partial.Count);
foreach (DancingLinks.Node <ColumnName> row in partial)
{
result.AddItem(GetRowName(row));
}
output.Solution(result);
results += 1;
}
else
{
DancingLinks.ColumnHeader <ColumnName> col = FindBestColumn();
if (col.size > 0)
{
CoverColumn(col);
DancingLinks.Node <ColumnName> row = col.down;
while (row != col)
{
partial.AddItem(row);
DancingLinks.Node <ColumnName> node = row.right;
while (node != row)
{
CoverColumn(node.head);
node = node.right;
}
results += Search(partial, output);
partial.Remove(partial.Count - 1);
node = row.left;
while (node != row)
{
UncoverColumn(node.head);
node = node.left;
}
row = row.down;
}
UncoverColumn(col);
}
}
return(results);
}
