private void TestMstAlgorithm(IWeightedGraph <int, double> graph, double expectedMstWeight, double precision, ALGORITHM algorithm)
{
// Build minimum spanning tree with algorithm to test
IWeightedGraph <int, double> msp;
switch (algorithm)
{
case ALGORITHM.KRUSKAL:
msp = Kruskal.FindMinimumSpanningTree(graph);
break;
case ALGORITHM.PRIM:
msp = Prim.FindMinimumSpanningTree(graph, 0, double.MaxValue);
break;
default:
throw new NotImplementedException($"No minimum spanning tree test implemented for algorithm {algorithm.ToString()}.");
}
// Check that all verteces are included
Assert.AreEqual(graph.VertexCount, msp.VertexCount);
// Count edges and compute total weight
IEnumerable <IWeightedEdge <int, double> > edges = msp.GetAllEdges();
int edgeCount = edges.Count();
double mspWeight = edges.Sum(e => e.Weight);
// Check edge count
Assert.AreEqual(graph.VertexCount - 1, edgeCount);
// Check that the total weight is as expected
AssertDoublesNearlyEqual(expectedMstWeight, mspWeight, precision);
}
public static IWeightedGraph <TV, TW> FindTour <TV, TW>(IWeightedGraph <TV, TW> graph) where TV : IEquatable <TV>
{
GraphBuilder <TV, TW> builder = new GraphBuilder <TV, TW>();
builder.AddVerteces(graph.GetAllVerteces().Select(v => v.Value));
// Find minimum spanning tree
IWeightedGraph <TV, TW> msp = Kruskal.FindMinimumSpanningTree(graph);
// Connect verteces in the order of the MSP
IVertex <TV> lastVertex = null;
DepthFirstSearch.Traverse(msp, currentVertex =>
{
if (lastVertex != null)
{
try
{
builder.AddEdge(lastVertex.Value, currentVertex.Value, graph.GetEdgeBetweenVerteces(lastVertex.Value, currentVertex.Value).Weight);
}
catch (VertecesNotConnectedException <TV> exception)
{
throw new GraphNotCompleteException("The graph is not complete.", exception);
}
}
lastVertex = currentVertex;
});
// Add closing edge
IVertex <TV> firstVertex = msp.GetFirstVertex();
IWeightedEdge <TV, TW> closingEdge = graph.GetEdgeBetweenVerteces(lastVertex.Value, firstVertex.Value);
builder.AddEdge(lastVertex.Value, firstVertex.Value, closingEdge.Weight);
// Done!
return(builder.Build());
}
