Prim算法优先级队列版 算法基础篇（四）

// Prim算法.cpp : 定义控制台应用程序的入口点。
//

#include "stdafx.h"
#include <stdio.h>
#include <string>
#include <queue>
#include <stdlib.h>
using namespace std;
#define Max 10
#define Infinity 1000
typedef unsigned int EdgeType;
typedef unsigned int DistType;
typedef int VexType;


struct Graph     //图结构 包括边点数，边数组，访问标记，从初始点到点的路径长度。
{
  int Arc;int Vex;
  EdgeType Edge[Max][Max];
  bool Vis[Max];
  DistType Dist[Max];
};

struct QueElem  //Que节点这个节点的设计主要是为了在使用优先级队列时比较方便
{
    VexType V;
    DistType D;
    friend bool operator > (struct QueElem  Q1,struct QueElem  Q2)
    {
        return Q1.D> Q2.D;
    }
};

typedef struct QueElem Q;

//priority_queue<Q,vector<Q>,greater<Q> > PriorQue;
priority_queue<Q,vector<Q>,greater<Q> > PriorQue;     //申明优先级队列，建立小顶堆。
 Q QueArr[Max];                                      //队列数组

void ReadGraph(Graph *G)                      //读图函数
{
    int x,y;
    int weigh;
    printf("请输入点数和边数！\n");
    scanf("%d%d",&(G->Vex),&(G->Arc));
    memset(G->Edge,-1,sizeof(G->Edge));
    memset(G->Vis,0,sizeof(G->Vis));
    memset(G->Dist,-1,sizeof(G->Dist));
    for(int i=0;i<G->Arc;i++)
    {
        printf("请输入第%d条边的起点终点和权值:",i+1);
        scanf("%d%d%u",&x,&y,&weigh);
        G->Edge[x][y]=weigh;
        G->Edge[y][x]=weigh;
    }
#if 0
    for(int i=0;i<G->Vex;i++)
    {
        Vis[i]=false;
        Dist[i]=Infinity;
    }
#endif

    G->Dist[0]=0;
    for(int i=0;i<Max;i++)
    {
        QueArr[i].V=i;
        QueArr[i].D=G->Dist[i];
    }

}


void Prim(Graph *G)         
{
    int i;
    Q pQ;
    PriorQue.push(QueArr[0]);//推入头数组元素 

    while(!PriorQue.empty())                    
    {
        pQ=PriorQue.top();             //这个语句要用好，他和那个operator函数息息相关，注意operator参数只能为引用或者原型，不能指针
        printf("pQ=%d\n",pQ.V);
        PriorQue.pop();
        G->Vis[pQ.V]=true;
        for(i=0;i<G->Vex;i++)
        {
            if(G->Edge[pQ.V][i]< Infinity && !(G->Vis[i]) )  //检验是否有边和是否已访问
            {
                if(G->Dist[pQ.V]+G->Edge[pQ.V][i]<G->Dist[i])
                {
                    G->Dist[i]=G->Dist[pQ.V]+G->Edge[pQ.V][i];
                    QueArr[i].D=G->Dist[i];
                }
                PriorQue.push(QueArr[i]);
            }
        }
    }
}




int _tmain(int argc, _TCHAR* argv[])
{
    Graph *G=(Graph *)malloc(sizeof (struct Graph));
    ReadGraph(G);
    Prime(G);
    for(int i=0;i<G->Vex;i++)
        printf("G->Dist[%d]=%u\n",i,G->Dist[i]);
    return 0;
}