private void Visit(EdgeWeightedGraph G, int v)
{
marked[v] = true;
foreach (Edge e in G.Adj(v))
{
int w = e.Other(v);
if (marked[w])
{
continue; //v-w失效
}
if (e.Weight < distTo[w])
{ //连接w和树的最佳边Edge变为e
edgeTo[w] = e; //保存w和最小生成树相连的边
distTo[w] = e.Weight; //即w和最小生成树最近的距离为e.Weight
if (pq.Contains(w))
{
pq.Change(w, distTo[w]);
}
else
{
pq.Insert(w, distTo[w]);
}
}
}
}//将顶点v添加到树中，更新数据
public DijkstraSP(EdgeWeightedDigraph G, int s)
{
edgeTo = new DirectedEdge[G.VNumber()];
distTo = new double[G.VNumber()];
pq = new IndexMinPQ <double>(G.VNumber());
for (int v = 0; v < G.VNumber(); v++)
{
distTo[v] = Double.PositiveInfinity;
}
distTo[s] = 0.0;
pq.Insert(s, 0.0);
while (!pq.IsEmpty())
{
Relax(G, pq.DelMin());
}
}
private IndexMinPQ <Double> pq; //有效的横切边
public PrimMST(EdgeWeightedGraph G)
{
edgeTo = new Edge[G.VNumber];
distTo = new double[G.VNumber];
marked = new bool[G.VNumber];
for (int v = 0; v < G.VNumber; v++)
{
distTo[v] = Double.PositiveInfinity;
}
pq = new IndexMinPQ <double>(G.VNumber);
distTo[0] = 0.0;
pq.Insert(0, 0.0); //用顶点0和权重0初始化pq
while (!pq.IsEmpty())
{
Visit(G, pq.DelMin()); //将最近的顶点添加到树中
}
}
private void Relax(EdgeWeightedDigraph G, int v)
{
foreach (DirectedEdge e in G.Adj(v))
{// v->w e:v和w相连的边
int w = e.To();
if (distTo[w] > distTo[v] + e.Weight())
{// 起点到达w点的路径 > 起点到达v的路径+e的权重
distTo[w] = distTo[v] + e.Weight();
edgeTo[w] = e;
if (pq.Contains(w))
{
pq.Change(w, distTo[w]);
}
else
{
pq.Insert(w, distTo[w]);
}
}
}
}
