Hi,

In graph theory this is called scheduling problem, and your particular kind of scheduling problem is called "Reverse topological sort" 8) There is no built-in algorithm to do that, but it is easy to implement:

Hashtable visitedNodes = new Hashtable();
int order = 0;

void TopologicalSort(Diagram diagram)
{
	foreach (DiagramNode node in diagram.Nodes)
	{
		if (!visitedNodes.ContainsKey(node))
			Search(node);
	}
}

void Search(DiagramNode node)
{
	visitedNodes[node] = true;
	foreach (DiagramLink link in node.OutgoingLinks)
	if (!visitedNodes.ContainsKey(link.Destination))
		Search(link.Destination);
	Process(node, order++);
}

void Process(DiagramNode node, int order)
{
	// process the node here
	if (node is ShapeNode)
		(node as ShapeNode).Text = order.ToString();
}
 

There is a very nice book with solutions to graph problems: "Algorithms in Java, Part 5: Graph Algorithms" by Robert Sedgewick, and the code above is one of the algorithms in the book adapted to the Flowchart.NET API.

This works only for acyclic graphs, because if there is a cycle, you won't have a well defined dependency order. You might use the PathFinder.FindCycle method to find and remove cycles before running that method.

I hope that helps,
Stoyan