public Kruskal(WeightedEdgeGraph G)
{
queue = new Queue <WeightedEdge>();
pq = new MinPQ <WeightedEdge>(G.GetE());
union = new int[G.GetV()];
for (int x = 0; x < union.Count(); x++)//初始化连通分量
{
union[x] = x;
}
foreach (var e in G.edges())//初始化优先队列
{
pq.insert(e);
}
while (!pq.IsEmpty() && queue.Count < G.GetV() - 1)
{
var minE = pq.DeletePQHead();//最短边
int v = minE.either();
int w = minE.other(v);
if (isConnect(v, w))
{
continue; //会形成环
}
queue.Enqueue(minE);
connect(v, w);//加入同一连通分量
}
}
public Prim(WeightedEdgeGraph G)
{
dic = new Dictionary <int, WeightedEdge>();
marked = new bool[G.GetV()];
queue = new Queue <WeightedEdge>();
visit(0, G);//从0节点开始
while (dic.Count > 0)
{
int i = GetMinEdge(); //最短横切边的非树顶点
queue.Enqueue(dic[i]); //最短横切边加入queue
dic.Remove(i);
visit(i, G); //i被加入树，并且重新计算横切边情况
}
}
/// <summary>
/// v被加入树。
/// 在图中和v相连但另一个节点是非树中的所有边中
/// 找出最短的那条，入字典，以供下次取最短横切边时使用
/// </summary>
/// <param name="v">要被加入树中的节点</param>
private void visit(int v, WeightedEdgeGraph G)
{
marked[v] = true;//v被加入树
foreach (var e in G.GetAdj(v))
{
int w = e.other(v);
if (marked[w])
{
continue;
}
if (dic.ContainsKey(w)) //w节点还连接到别的树节点上
{
if (dic[w].GetWeight() > e.GetWeight()) //此时e权重更短的话，进行替换
{
dic[w] = e;
}
}
else//w节点还没连接到别的树节点上
{
dic.Add(w, e);
}
}
}
