/// <summary>
/// Remove the edge (u,v) from the graph.
/// If the graph allows parallel edges this remove all occurrences of
/// (u,v).
/// </summary>
/// <param name="u">source vertex</param>
/// <param name="v">target vertex</param>
public virtual void RemoveEdge(Vertex u, Vertex v)
{
if (u == null)
throw new ArgumentNullException("u");
if (v == null)
throw new ArgumentNullException("v");
this.version++;
// getting out-edges
EdgeCollection outEdges = this.vertexOutEdges[u];
// marking edges to remove
EdgeCollection removedEdges = new EdgeCollection();
foreach(Edge e in outEdges)
{
if (e.Target == v)
removedEdges.Add(e);
}
//removing out-edges
foreach(Edge e in removedEdges)
outEdges.Remove(e);
removedEdges.Clear();
EdgeCollection inEdges = this.vertexInEdges[v];
foreach(Edge e in inEdges)
{
if (e.Source == u)
removedEdges.Add(e);
}
//removing in-edges
foreach(Edge e in removedEdges)
inEdges.Remove(e);
}