private void visit(EdgeWightedGraph g, Int32 v)
{
marked[v] = true;
foreach (Edge e in g.Adj(v))
{
int w = e.Other(v);
if (marked[w])
{
continue;//访问过了
}
if (e.Weight < disTo[w])
{
//从MST到w的距离变短了。最佳边变成e
edgeTo[w] = e;
disTo[w] = e.Weight;
if (pq.Contains(w))
{
pq.Change(w, disTo[w]);
}
else
{
pq.Insert(w, disTo[w]);
}
}
}
}
public KruskalMST(EdgeWightedGraph g)
{
mst = new Edge[g.V - 1]; //保存边序列
var pq = new Chapter2.SortDemos.BinaryHeap <Edge>(g.E, (Edge e1, Edge e2) => e1.Weight < e2.Weight); //最小堆
foreach (var edge in g.Edges())
{
pq.Insert(edge);
}
var uf = new Chapter1.UnionFindDemo.UnionFind(g.V);//判断v是否已经在一个子树中
int index = 0;
while (!pq.IsEmpty())
{
var edge = pq.Delete();
int v = edge.Either(); int w = edge.Other(v);
if (uf.IsConnected(v, w))//不在一个子树中（一个连通分量）
{
continue;
}
uf.Union(v, w);
mst[index++] = edge;
weight += edge.Weight;
}
}
private Chapter2.SortDemos.IndexPriorityQueue <Double> pq; //保存最小边的最小堆
public PrimMST(EdgeWightedGraph g)
{
pq = new Chapter2.SortDemos.IndexPriorityQueue <double>(g.V, (Double s, Double b) =>
{
return(s < b);
});//允许的标号[0,g.V]
edgeTo = new Edge[g.V];
marked = new Boolean[g.V];
disTo = new Double[g.V];
for (Int32 v = 0; v < g.V; ++v)
{
disTo[v] = Double.PositiveInfinity; //表示为正无穷
}
pq.Insert(0, 0.0);
disTo[0] = 0.0;
while (!pq.IsEmpty())
{
visit(g, pq.DeleteMin());//获取二叉堆中总是最小的索引
}
}
