最小生成树之Kruskal算法

问题：关键还是定义数据结构问题，还有如何把两个集合合并成一个。

代码：

#include <iostream>

#include <cstdlib>

using namespace std;



#define MAXV 20

#define INFINITY 65535

typedef struct node

{

	int from;

	int to;

	int weight;

}WGraph;

typedef struct map

{

	WGraph arr[MAXV];

	int vexs,edges;

}*Map;



void createGraph(Map &map)                          //创建图

{

	int i;

	cout<<"please input the edges and vexs:";

	cin>>map->edges>>map->vexs;

	for(i=0;i<map->edges;i++)

	{

		cout<<"please input from,to,weight of graph:";

		cin>>map->arr[i].from>>map->arr[i].to>>map->arr[i].weight;

	}

}



void showGraph(Map wg)

{

    int i;

	cout<<"the num of edges and vexs:";

	cout<<wg->edges<<"   "<<wg->vexs<<endl;

	for(i=0;i<wg->edges;i++)

	{

		cout<<"("<<wg->arr[i].from<<","<<wg->arr[i].to<<"   "<<wg->arr[i].weight<<")"<<endl;

	}

	cout<<endl;

}



void MST_Kruskal(Map map)

{

	int set[MAXV];

	int min;

	int i,j,k,s;

	int temp;

	int flag;                                 //访问标志

	for(i=0;i<map->edges;i++)

	{

		set[i]=i;

	}

	for(j=0;j<map->vexs-1;j++)   //共有n-1条边

	{

		min=INFINITY;

		for(k=0;k<map->edges;k++)                                //查找最小边

		{

			if(set[map->arr[k].from]!=set[map->arr[k].to])

			{

				if(map->arr[k].weight<min)

				{

				min=map->arr[k].weight;

				temp=k;

				}

			}	

		}

		flag=set[map->arr[temp].to];

		for(s=0;s<map->edges;s++)                        //把两个集合合并成一个集合

		{

			if(set[s]==flag)

				set[s]=set[map->arr[temp].from];

		}

		cout<<"("<<map->arr[temp].from<<","<<map->arr[temp].to<<","<<map->arr[temp].weight<<")"<<endl;    //输出最小生成树



	}



}



int main()

{

	Map map;

	map=(Map)malloc(MAXV*sizeof(struct map));

	cout<<"create the map:"<<endl;

	createGraph(map);

	cout<<"output the map";

	showGraph(map);

	cout<<"mst_kruskal :"<<endl;

	MST_Kruskal(map);

	cout<<endl;

	return 0;

}

 运行截图：