算法-图论-最小生成树-Prim

利用最小索引堆优化prim

#include <iostream>
#include <vector>
#include <cassert>
#include "Edge.h"
#include "IndexMinHeap.h"

using namespace std;

template<typename Graph,typename Weight>
class PrimMST
{
private:
    Graph &G;
    IndexMinHeap<Weight> ipq;
    vector<Edge<Weight>*> edgeTo;
    bool* marked;
    vector<Edge<Weight>> mst;
    Weight mstWeight;

    void visit(int v){
        assert(!marked[v])
        marked[v] = true;
        typename Graph::adjIterator adj(G.v);
        for(Edge<Weight>* e = adj.begin();!adj.end();e=adj.next()){
            int w = e->other(v);//相邻的顶点
            if(!marked[w]){
                if(!edgeTo[w]){
                    ipq.insert(w,e->wt());
                    edgeTo[w]=e;
                }else if(e->wt() < edgeTo[w]->wt()){
                    edgeTo[w]=e;
                    ipq.change(w,e->wt());
                }
            }
        }
    }
public:
    PrimMST(Graph &graph):G(graph),ipq(IndexMinHeap<double>(graph.V())){
        marked = new bool[G.V()];
        for(int i =0;i<G.V();i++){
            marked[i] = false;
            edgeTo.push_back(NULL);
        }
        mst.clear();

        //Prim
        visit(0);
        while (!ipq.isEmpty())
        {
            int v = ipq.extractMinIndex();
            assert(edgeTo[v]);
            mst.push_back(*edgeTo[v]);
            visit(v);
        };
        mstWeight = mst[0].wt();
        for(int i =1;i<mst.size();i++)
            mstWeight += mst[i].wt();
        
    };
    ~PrimMST(){
        delete[] marked;
    };
    vector<Edge<Weight>> mstEdges(){
        return mst;
    };
    Weight result(){
        return mstWeight;
    }

};