#define infinity 1000000
#define max_vertexes 5 

typedef int Graph[max_vertexes][max_vertexes];

void prim(Graph G,int vcount,int father[])
{
    int i,j,k;
    int lowcost[max_vertexes],closeset[max_vertexes],used[max_vertexes];
    for (i=0;i<vcount;i++)
   {
        lowcost[i]=G[0][i];
        closeset[i]=0; 
        used[i]=0;
        father[i]=-1; 
   }
    used[0]=1; 
    for (i=1;i<vcount;i++)
   {
        j=0;
        while (used[j])
              j++;
        for (k=0;k<vcount;k++)
            if ((!used[k])&&(lowcost[k]<lowcost[j]))
                      j=k;
        father[j]=closeset[j]; 
        used[j]=1;
        for (k=0;k<vcount;k++)
            if (!used[k]&&(G[j][k]<lowcost[k]))
            {
                 lowcost[k]=G[j][k];
                 closeset[k]=j;
           }
    }
}

Prim算法求最小生成树