public void CheckPredecessorDoubleLineGraph() { AdjacencyGraph g = new AdjacencyGraph(true); IVertex v1 = g.AddVertex(); IVertex v2 = g.AddVertex(); IVertex v3 = g.AddVertex(); IEdge e12 = g.AddEdge(v1,v2); IEdge e23 = g.AddEdge(v2,v3); IEdge e13 = g.AddEdge(v1,v3); EdgeDoubleDictionary weights = DijkstraShortestPathAlgorithm.UnaryWeightsFromEdgeList(g); DijkstraShortestPathAlgorithm dij = new DijkstraShortestPathAlgorithm(g,weights); PredecessorRecorderVisitor vis = new PredecessorRecorderVisitor(); dij.RegisterPredecessorRecorderHandlers(vis); dij.Compute(v1); EdgeCollection col = vis.Path(v2); Assert.AreEqual(1,col.Count); Assert.AreEqual(e12,col[0]); col = vis.Path(v3); Assert.AreEqual(1,col.Count); Assert.AreEqual(e13,col[0]); }
/// <summary> /// Computes a set of eulerian trail, starting at <paramref name="s"/> /// that spans the entire graph. /// </summary> /// <remarks> /// <para> /// This method computes a set of eulerian trail starting at <paramref name="s"/> /// that spans the entire graph.The algorithm outline is as follows: /// </para> /// <para> /// The algorithms iterates throught the Eulerian circuit of the augmented /// graph (the augmented graph is the graph with additional edges to make /// the number of odd vertices even). /// </para> /// <para> /// If the current edge is not temporary, it is added to the current trail. /// </para> /// <para> /// If the current edge is temporary, the current trail is finished and /// added to the trail collection. The shortest path between the /// start vertex <paramref name="s"/> and the target vertex of the /// temporary edge is then used to start the new trail. This shortest /// path is computed using the <see cref="BreadthFirstSearchAlgorithm"/>. /// </para> /// </remarks> /// <param name="s">start vertex</param> /// <returns>eulerian trail set, all starting at s</returns> /// <exception cref="ArgumentNullException">s is a null reference.</exception> /// <exception cref="Exception">Eulerian trail not computed yet.</exception> public EdgeCollectionCollection Trails(IVertex s) { if (s==null) throw new ArgumentNullException("s"); if (this.Circuit.Count==0) throw new Exception("Circuit is empty"); // find the first edge in the circuit. int i=0; for(i=0;i<this.Circuit.Count;++i) { IEdge e = this.Circuit[i]; if (TemporaryEdges.Contains(e)) continue; if (e.Source == s) break; } if (i==this.Circuit.Count) throw new Exception("Did not find vertex in eulerian trail?"); // create collections EdgeCollectionCollection trails = new EdgeCollectionCollection(); EdgeCollection trail = new EdgeCollection(); BreadthFirstSearchAlgorithm bfs = new BreadthFirstSearchAlgorithm(VisitedGraph); PredecessorRecorderVisitor vis = new PredecessorRecorderVisitor(); bfs.RegisterPredecessorRecorderHandlers(vis); bfs.Compute(s); // go throught the edges and build the predecessor table. int start = i; for (;i<this.Circuit.Count;++i) { IEdge e = this.Circuit[i]; if (TemporaryEdges.Contains(e)) { // store previous trail and start new one. if(trail.Count != 0) trails.Add(trail); // start new trail // take the shortest path from the start vertex to // the target vertex trail = vis.Path(e.Target); } else trail.Add(e); } // starting again on the circuit for (i=0;i<start;++i) { IEdge e = this.Circuit[i]; if (TemporaryEdges.Contains(e)) { // store previous trail and start new one. if(trail.Count != 0) trails.Add(trail); // start new trail // take the shortest path from the start vertex to // the target vertex trail = vis.Path(e.Target); } else trail.Add(e); } // adding the last element if (trail.Count!=0) trails.Add(trail); return trails; }
public EdgeCollectionCollection Trails(IVertex s) { if (s == null) { throw new ArgumentNullException("s"); } if (this.Circuit.Count == 0) { throw new Exception("Circuit is empty"); } int num = 0; num = 0; while (num < this.Circuit.Count) { IEdge edge = this.Circuit.get_Item(num); if (!this.TemporaryEdges.Contains(edge) && (edge.get_Source() == s)) { break; } num++; } if (num == this.Circuit.Count) { throw new Exception("Did not find vertex in eulerian trail?"); } EdgeCollectionCollection collections = new EdgeCollectionCollection(); EdgeCollection edges = new EdgeCollection(); BreadthFirstSearchAlgorithm algorithm = new BreadthFirstSearchAlgorithm(this.VisitedGraph); PredecessorRecorderVisitor vis = new PredecessorRecorderVisitor(); algorithm.RegisterPredecessorRecorderHandlers(vis); algorithm.Compute(s); int num2 = num; while (num < this.Circuit.Count) { IEdge edge2 = this.Circuit.get_Item(num); if (this.TemporaryEdges.Contains(edge2)) { if (edges.Count != 0) { collections.Add(edges); } edges = vis.Path(edge2.get_Target()); } else { edges.Add(edge2); } num++; } for (num = 0; num < num2; num++) { IEdge edge3 = this.Circuit.get_Item(num); if (this.TemporaryEdges.Contains(edge3)) { if (edges.Count != 0) { collections.Add(edges); } edges = vis.Path(edge3.get_Target()); } else { edges.Add(edge3); } } if (edges.Count != 0) { collections.Add(edges); } return collections; }