HDU1162-Eddy's picture

http://acm.hdu.edu.cn/showproblem.php?pid=1162

#include<stdio.h>
#include<math.h>
#include<string.h>
#define INF 0x3f3f3f3f
#define N 110
struct Node
{
    double x,y;
}node[N];
int vis[N],n;
double map[N][N],dis[N];
void prim()
{
    int i,j,k;
    double min,sum=0;
    memset(vis,0,sizeof(vis));
    vis[0]=1;
    for(i=1;i<n;i++)  
       dis[i]=map[0][i];
    for(i=1;i<n;i++)
    {
        min=INF;
        for(j=0;j<n;j++)
           if(!vis[j]&&min>dis[j])
           {
                  min=dis[j];
               k=j;
           }
        if(min==INF)
           break;
        sum+=min;
        vis[k]=1;
        for(j=0;j<n;j++)
           if(!vis[j]&&dis[j]>map[k][j])
              dis[j]=map[k][j]; 
    }
    printf("%.2lf\n",sum);   
} 
int main(void)
{
    int i,j;
    while(scanf("%d",&n)!=EOF)
    {
        for(i=0;i<n;i++)
           scanf("%lf%lf",&node[i].x,&node[i].y);
        for(i=0;i<n;i++)
           for(j=0;j<n;j++)
           {
                  if(i==j)
                  map[i][j]=0;
               else
                  map[i][j]=sqrt((node[i].x-node[j].x)*(node[i].x-node[j].x)+(node[i].y-node[j].y)*(node[i].y-node[j].y));
           }  
        prim();  
    }    
    return 0;
}