/// <summary>
/// Add a row connecting the nodes to the circular linked nodes for each column.
/// </summary>
/// <param name="values"></param>
/// <param name="row"></param>
/// <returns></returns>
private DlxNode AddNodeRow(ICollection <int> values, int row)
{
DlxNode rv = null;
DlxNode leftNode = null;
foreach (var item in values)
{
var headerColumn = _columnHeaders[item];
var newNode = new DlxNode(new PuzzleCoordinate(row, item))
{
Header = headerColumn,
Left = leftNode,
Right = null
};
headerColumn.AddNode(newNode);
rv ??= newNode;
rv.Left = newNode;
newNode.Right = rv;
if (leftNode != null)
{
leftNode.Right = newNode;
}
leftNode = newNode;
}
return(rv);
}
/// <summary>
/// Add a new row Dlx node to the end of a column.
/// </summary>
/// <param name="newNode"></param>
public void AddNode(DlxNode newNode)
{
var upNode = Up;
newNode.Up = upNode;
newNode.Down = this;
upNode.Down = newNode;
Up = newNode;
NodeCount++;
}