201412-4-最优灌溉

(http://115.28.138.223/view.page?gpid=T18)

#include<cstdio>#include<vector>#include<cstring>#define INF 0xfffffff#define maxn 1005using namespace std;int dis[maxn],edge[maxn][maxn];bool vis[maxn];int n,m,u,v,w,mi;void Prim()//点归并 {    int i,j,k,ans=0;    memset(vis,0,sizeof(vis));    for(i=1;i<=n;i++)       dis[i]=edge[1][i];    vis[1]=1;    for(i=1;i<n;i++)    {        mi=INF;        for(j=1;j<=n;j++)        {            if(!vis[j]&&dis[j]<mi)            {                mi=dis[j];                k=j;            }        }        vis[k]=1;        ans+=mi;//ans为距离之和         for(j=1;j<=n;j++)           if(!vis[j]&&dis[j]>edge[k][j])              dis[j]=edge[k][j];     }     printf("%d\n",ans);}int main(){    scanf("%d%d",&n,&m);    for(int i=1;i<=n;i++)        for(int j=1;j<=n;j++)            edge[i][j]=INF;//非邻接顶点距离用INF标记     for(int i=0;i<m;i++)    {        scanf("%d%d%d",&u,&v,&w);        edge[u][v]=w;        edge[v][u]=w;    }       Prim();    return 0;}