private void Search(DancingLinks.HeaderNode pHeader)
{
//If our matrix is empty we have our solution
if (pHeader == _links.Root)
{
if (SolutionFound != null)
{
SolutionFound(BuildSolution());
}
}
else
{
//Cover this header
pHeader.Cover();
//Cycle through the column
DancingLinks.Node column = pHeader.Down;
while (column != pHeader)
{
//Add the row to our solution
_solutionList.Add(column);
//Add the row to our solution and cover the columns in this row
DancingLinks.Node row = column.Right;
while (row != column)
{
row.Header.Cover();
_solutionList.Add(row);
row = row.Right;
}
//Recurse with our reduced matrix
Search(ChooseHeaderNode());
_solutionList.Remove(column);
//Uncover the columns in the row to return our matrix to normal so recursion doesn't break
row = column.Left;
while (row != column)
{
row.Header.Uncover();
_solutionList.Remove(row);
row = row.Left;
}
column = column.Down;
}
pHeader.Uncover();
}
}
/// <summary>
/// Chooses the header node with the least amount of nodes connected to it
/// </summary>
private DancingLinks.HeaderNode ChooseHeaderNode()
{
DancingLinks.HeaderNode node = (DancingLinks.HeaderNode)_links.Root.Right;
DancingLinks.HeaderNode retval = node;
while (node != _links.Root)
{
if (node.Count < retval.Count)
{
retval = node;
}
node = (DancingLinks.HeaderNode)node.Right;
}
return(retval);
}