public IEnumerable <Edge <TVertex> > Execute(TGraph graph)
{
if (graph == null)
{
throw new ArgumentNullException(nameof(graph));
}
if (_connectedComponentsCounter.Execute(graph) > 1)
{
throw new InvalidOperationException("For Kruskal's algorithm graph cannot contain more than one connected component");
}
var edges = graph.ReducedEdges;
var sortedEdgeWeightEntries = graph.Weights.Where(w => edges.Contains(w.Key))
.OrderBy(w => w.Value)
.ToList();
var graphCopy = new UndirectedWeightedGraph <TVertex, int>(graph.Vertices) as TGraph;
var spanningTreeEdges = new List <Edge <TVertex> >();
foreach (var edgeWeightEntry in sortedEdgeWeightEntries)
{
var edge = edgeWeightEntry.Key;
var weight = edgeWeightEntry.Value;
graphCopy.AddUndirectedEdge(edge.Source, edge.Destination, weight);
if (IsAnyCycleDetected(graphCopy))
{
graphCopy.RemoveUndirectedEdge(edge.Source, edge.Destination);
}
else
{
spanningTreeEdges.Add(new Edge <TVertex>(edge.Source, edge.Destination));
}
}
return(spanningTreeEdges);
}