/*********************************************
*@time 2016/08/10 21:46
*@description prim算法求最小生成树
*@author dzq
**********************************************/
#include<cstdio>
#include<iostream>
#include<cstring>
#include<algorithm>
#define INF 1<<30
using namespace std;
/****************************************************
*@函数名 prim
*@parameter int *route 将路径保存在一个一维数组中
*@parameter num_Of_Node 图中节点的数量
*@返回值 int 最小生成树的大小
*@description prim算法求最小生成树;每找到一个离生成树的点,就将其加入最小生成树(visit=true),再更新其他节点到树的距离
************************************************************/
int prim(int *route,int num_Of_Node)
{
int dis[num_Of_Node];
bool visit[num_Of_Node];
int shortest_Distance=0;
memset(visit,0,sizeof(visit));
int last_Add_Node=0;//离生成树最近的点
int nearest_Distance=INF;
for(int i=0;i<num_Of_Node;i++)
{
dis[i]=INF;
}
visit[0]=true;
for(int i=1;i<num_Of_Node;i++)
{
// printf("last_Add_Node=%c\n",last_Add_Node+'A');
int nearest_Node;
nearest_Distance=INF;
for(int j=0;j<num_Of_Node;j++)//根据nearest_Distance更新不在最小树的点到最小数的距离
{
if(!visit[j]&&dis[j]>route[last_Add_Node*num_Of_Node+j])//route[last_Add_Node*m+j]=route[last_Add_Node][i]
{
// printf("%d %d %d\n",last_Add_Node,i,route[last_Add_Node*num_Of_Node+j]);
dis[j]=route[last_Add_Node*num_Of_Node+j];//更新最小生成树的总距离
if(dis[j]==0) printf("%d %d %d\n",last_Add_Node,i,route[last_Add_Node*num_Of_Node+j]);
}
}
for(int j=0;j<num_Of_Node;j++)//找到离最小树最近的点
{
if(!visit[j]&&nearest_Distance>dis[j])
{
nearest_Distance=dis[j];
nearest_Node=j;
}
}
shortest_Distance+=nearest_Distance;
last_Add_Node=nearest_Node;
visit[last_Add_Node]=true;
printf("last_Add_Node=%c,nearest_Distance=%d\n",last_Add_Node+'A',nearest_Distance);
printf("shortest_Distance=%d\n",shortest_Distance);
}
return shortest_Distance;
}
int main()
{
int num_Of_Node;
int* route;
printf("Please input the num of node\n");
scanf("%d",&num_Of_Node);
route=(int *)malloc( num_Of_Node*num_Of_Node*sizeof(int));
for(int i=0;i<num_Of_Node;i++)
{
for(int j=0;j<num_Of_Node;j++)
{
route[i*num_Of_Node+j]=INF;
}
}
printf("Please input all node and dis\n");
int route_Begin_Node;
int route_End_Node;
int distance;
while(scanf("%d %d %d",&route_Begin_Node,&route_End_Node,&distance))
{
if(route_Begin_Node==route_End_Node) break;
route[route_Begin_Node*num_Of_Node+route_End_Node]=distance;
route[route_End_Node*num_Of_Node+route_Begin_Node]=distance;//无向图
}
int shortest_Distance=prim(route,num_Of_Node);
printf("The shortest_Distance is %d",shortest_Distance);
}
/*************
用例
7
0 1 7
0 3 5
1 2 8
1 3 9
1 4 7
2 4 5
3 4 15
3 5 6
4 5 8
4 6 9
5 6 11
0 0 0
*/