public bool HasDirectedCycle()
{
DirectedGraph tempGraph = (DirectedGraph)this.Clone();
tempGraph.ComputeStronglyConnectedComponents(null);
IEnumerable <GraphNode> query = (from node1 in tempGraph.Nodes
from node2 in tempGraph.Nodes
where ((!node1.Name.Equals(node2.Name)) &&
node1.ComponentNumber == node2.ComponentNumber)
select node1);
return(query != null && query.Count() > 0);
}
public bool AdditionalEdgeInducesDirectedCycle(DirectedGraphEdge additionalEdge)
{
DirectedGraph tempGraph = (DirectedGraph)this.Clone();
tempGraph.AddEdge(additionalEdge);
tempGraph.ComputeStronglyConnectedComponents(null);
List <GraphNode> query = (from node1 in tempGraph.Nodes
from node2 in tempGraph.Nodes
where ((!node1.Name.Equals(node2.Name)) &&
node1.ComponentNumber == node2.ComponentNumber)
select node1).ToList();
return(query != null && query.Count() > 0);
}
public bool EdgeReversalInducesDirectedCycle(DirectedGraphEdge edge)
{
DirectedGraph tempGraph = (DirectedGraph)this.Clone();
tempGraph.RemoveEdge(edge.From, edge.To);
tempGraph.AddEdge(new DirectedGraphEdge(edge.To, edge.From, edge.Cost));
tempGraph.ComputeStronglyConnectedComponents(null);
List <GraphNode> query = (from node1 in tempGraph.Nodes
from node2 in tempGraph.Nodes
where ((!node1.Name.Equals(node2.Name)) &&
node1.ComponentNumber == node2.ComponentNumber)
select node1).ToList();
return(query != null && query.Count() > 0);
}
