public static FlowGraph <T> FordFulkerson <T>(this FlowGraph <T> graph)
{
if (graph.Edges.Where(e => !e.Capacity.HasValue).Any())
{
throw new ArgumentException("In dem Graphen muss für jede Kante eine Kapazität definiert sein.");
}
// Sicherstellen, dass der Fluss bei allen Kanten initialisiert ist.
foreach (Edge <T> e in graph.Edges.Where(e => !e.Flow.HasValue))
{
e.Flow = 0;
}
// Eine Kopie des Graphens erstellen.
FlowGraph <T> maxFlowGraph = graph.Copy();
// Den Residualgraph erstellen
FlowGraph <T> residualGraph = maxFlowGraph.GetResidualGraph();
while (residualGraph.DepthFirstSearch(residualGraph.Source, residualGraph.Target, out List <Edge <T> > path))
{
int minAugmentingFlow = path.Select(e => Math.Abs(e.Flow.Value)).Min();
foreach (Edge <T> edge in path)
{
//Edge<T> edgeToModify = maxFlowGraph.Edges.Where(e => e.From.Equals(edge.From) && e.To.Equals(edge.To)).Single();
Edge <T> edgeToModify = maxFlowGraph.GetEdge(edge.From, edge.To);
if (edge.Flow.Value > 0)
{
edgeToModify.Flow += minAugmentingFlow;
}
else
{
edgeToModify.Flow -= minAugmentingFlow;
}
// edgeToModify.Flow += edge.Flow;
}
residualGraph = maxFlowGraph.GetResidualGraph();
}
return(maxFlowGraph);
}
public void Copy_must_work()
{
Vertex<string> source = new Vertex<string>("s");
Vertex<string> target = new Vertex<string>("t");
FlowGraph<string> flowGraph = new FlowGraph<string>(source, target, new List<Vertex<string>>() { source, target });
flowGraph.AddVertex("a");
flowGraph.AddVertex("b");
flowGraph.AddEdge("s", "a", 5, 2);
flowGraph.AddEdge("s", "b", 8, 4);
flowGraph.AddEdge("a", "b", 3, 0);
flowGraph.AddEdge("a", "t", 4, 2);
flowGraph.AddEdge("b", "t", 6, 4);
FlowGraph<string> flowGraphCopy = flowGraph.Copy();
Assert.IsFalse(ReferenceEquals(flowGraph.Vertices, flowGraphCopy.Vertices));
Assert.IsFalse(ReferenceEquals(flowGraph.Edges, flowGraphCopy.Edges));
Assert.IsFalse(ReferenceEquals(flowGraph.Vertices[0], flowGraphCopy.Vertices[0]));
Assert.IsFalse(ReferenceEquals(flowGraph.Edges[0], flowGraphCopy.Edges[0]));
}
public static FlowGraph InstantiateFlow(this FlowGraph flowGraph)
{
return(flowGraph.Copy() as FlowGraph);
}
