void Kruskal(Graph& G, Edge* &MST) { ParTree<int> A(G.VerticesNum()); //等价类 MinHeap<Edge> H(G.EdgesNum()); //最小值堆(minheap) MST=new Edge[G.VerticesNum()-1]; //最小支撑树 int MSTtag=0; //最小支撑树边的标号 for(int i=0; i<G.VerticesNum(); i++) //将图的所有边插入最小值堆H中 for(Edge e= G. FirstEdge(i); G.IsEdge(e);e=G. NextEdge(e)) if(G.FromVertex(e)< G.ToVertex(e)) //因为是无向图,所以应防止重复插入 H.Insert(e); int EquNum=G.VerticesNum(); //开始时有|V|个等价类 while(EquNum>1) { //合并等价类 Edge e=H.RemoveMin(); //获得下一条权最小的边 if(e.weight==INFINITE) { cout << "不存在最小支撑树." <<endl; delete [] MST; //释放空间 MST=NULL; //MST是空数组 return; } int from=G.FromVertex(e); //记录该条边的信息 int to= G.ToVertex(e); if(A.Different(from,to)) { //如果边e的两个顶点不在一个等价类 A.Union(from,to); //将边e的两个顶点所在的两个等价类合并为一个 AddEdgetoMST(e,MST,MSTtag++); //将边e加到MST EquNum--; //将等价类的个数减1 } } }
//Dijkstra算法,其中参数G是图,参数s是源顶点,D是保存最短距离及其路径的数组 void Dijkstra(Graph& G, int s, Dist* &D) { D = new Dist[G. VerticesNum()]; // D数组 for (int i = 0; i < G.VerticesNum(); i++) { // 初始化Mark数组、D数组 G.Mark[i] = UNVISITED; D[i].index = i; D[i].length = INFINITE; D[i].pre = s; } D[s].length = 0; MinHeap<Dist> H(G. EdgesNum()); // 最小值堆(minheap) H.Insert(D[s]); for (i = 0; i < G.VerticesNum(); i++) { bool FOUND = false; Dist d; while (!H.isEmpty()) { d = H.RemoveMin(); if(G.Mark[d.index]==UNVISITED) { //打印出路径信息 cout<< "vertex index: " <<d.index<<" "; cout<< "vertex pre : " <<d.pre <<" "; cout<< "V0 --> V" << d.index <<" length : " <<d.length<<endl; } if (G.Mark[d.index] == UNVISITED) { //找到距离s最近的顶点 FOUND = true; break; } } if (!FOUND) break; int v = d.index; G.Mark[v] = VISITED; // 把该点加入已访问组 // 因为v的加入,需要刷新v邻接点的D值 for (Edge e = G.FirstEdge(v); G.IsEdge(e);e = G.NextEdge(e)) if (D[G.ToVertex(e)].length > (D[v].length+G.Weight(e))) { D[G.ToVertex(e)].length = D[v].length+G.Weight(e); D[G.ToVertex(e)].pre = v; H.Insert(D[G.ToVertex(e)]); } } }