private Queue <Edge> mst = new Queue <Edge>(); // edges in MST
/**
* Compute a minimum spanning tree (or forest) of an edge-weighted graph.
* @param G the edge-weighted graph
*/
public KruskalMST(EdgeWeightedGraph G)
{
// more efficient to build heap by passing array of edges
MinPQ <Edge> pq = new MinPQ <Edge>();
foreach (Edge e in G.Edges)
{
pq.Insert(e);
}
// run greedy algorithm
UF uf = new UF(G.V);
while (!pq.IsEmpty && mst.Size < G.V - 1)
{
Edge e = pq.DeleteMin();
int v = e.Either;
int w = e.other(v);
if (!uf.Connected(v, w))
{ // v-w does not create a cycle
// merge v and w components
uf.Union(v, w);
mst.Enqueue(e); // add edge e to mst
weight += e.Weight;
}
}
// check optimality conditions
//assert ;
Contract.Assert(check(G));
}
public override ArrayPQBase <TKey> Clone()
{
// return new MinPQ<TKey>(this.pq, this.comparator);
var clone = new MinPQ <TKey>(this.pq.Length);
clone.n = this.n;
clone.pq = this.pq;
clone.comparator = this.comparator;
return(clone);
}
private MinPQ <Edge> pq; // edges with one endpoint in tree
/**
* Compute a minimum spanning tree (or forest) of an edge-weighted graph.
* @param G the edge-weighted graph
*/
public LazyPrimMST(EdgeWeightedGraph G)
{
mst = new Queue <Edge>();
pq = new MinPQ <Edge>();
marked = new bool[G.V];
for (int v = 0; v < G.V; v++) // run Prim from all vertices to
{
if (!marked[v])
{
prim(G, v); // get a minimum spanning forest
}
}
// check optimality conditions
//Contracts.Assert (G);
}