public void PostOrderTest()
{
var graph = new Graph();
graph.Nodes.Add("0");
graph.Nodes.Add("1");
graph.Nodes.Add("2");
graph.Nodes.Add("3");
graph.Nodes.Add("4");
graph.Edges.Add("0", "2");
graph.Edges.Add("2", "1");
graph.Edges.Add("1", "0");
graph.Edges.Add("0", "3");
graph.Edges.Add("3", "4");
var traversal = new DepthFirstTraversal();
var recorder = new PostOrderRecorder(traversal);
traversal.Run(graph.Nodes["0"]);
var order = recorder.GetOrder();
Assert.Equal(order.Count, graph.Nodes.Count);
Assert.All(graph.Nodes, n => Assert.True(order.IndexOf(graph.Nodes["0"]) >= order.IndexOf(n)));
Assert.True(order.IndexOf(graph.Nodes["1"]) < order.IndexOf(graph.Nodes["2"]));
Assert.True(order.IndexOf(graph.Nodes["4"]) < order.IndexOf(graph.Nodes["3"]));
}
public static ICollection <ISet <Node> > FindStronglyConnectedComponents(this Node entrypoint)
{
var graph = entrypoint.ParentGraph;
var traversal = new DepthFirstTraversal();
var recorder = new PostOrderRecorder(traversal);
traversal.Run(entrypoint);
var transpose = graph.Transpose();
var visited = new HashSet <Node>();
var result = new List <ISet <Node> >();
foreach (var node in recorder.GetOrder().Reverse())
{
if (!visited.Contains(node))
{
var subTraversal = new DepthFirstTraversal();
var component = new HashSet <Node>();
subTraversal.NodeDiscovered += (sender, args) =>
{
if (visited.Add(graph.Nodes[args.NewNode.Name]))
{
args.ContinueExploring = true;
component.Add(graph.Nodes[args.NewNode.Name]);
}
};
subTraversal.Run(transpose.Nodes[node.Name]);
result.Add(component);
}
}
return(result);
}