public LazyPrimMST(IEdgeWeightGraph g)
{
pq = new MinPQ <IEdge>();
marked = new bool[g.V];
mst = new Chapter1.Queue <IEdge>();
Visit(g, 0);//假设G是联通的
while (!pq.IsEmpty)
{
IEdge e = pq.Delete(); //找到权重最小的边
int v = e.Either;
int w = e.Other(v);
if (marked[v] && marked[w]) //跳过失效的边
{
continue;
}
mst.Enqueue(e); //将边添加到树中
if (!marked[v])
{
Visit(g, v);
}
if (!marked[w])
{
Visit(g, w);
}
}
}
private Node BuildTrie(int[] freq)
{
MinPQ <Node> pq = new MinPQ <Node>();
for (char c = (char)0; c < (char)R; c++)
{
if (freq[c] > 0)
{
pq.Insert(new Node(c, freq[c], null, null));
}
}
while (pq.Size > 1)
{
Node x = pq.Delete();
Node y = pq.Delete();
Node parent = new Node('\0', x.freq + y.freq, x, y);
pq.Insert(parent);
}
return(pq.Delete());
}
public KruskalMST(IEdgeWeightGraph G)
{
mst = new Chapter1.Queue <IEdge>();
MinPQ <IEdge> pq = new MinPQ <IEdge>();
foreach (var e in G.Edges())
{
pq.Insert(e);
}
UF uf = new UF(G.V);
while (!pq.IsEmpty && mst.Size < G.V - 1)
{
IEdge e = pq.Delete(); //找到权重最小的边
int v = e.Either, w = e.Other(v);
if (uf.Connected(v, w)) //忽略失效的边
{
continue;
}
uf.Union(v, w);
mst.Enqueue(e);
}
}