> #include <cstdio>
> #include <cstring>
> #include <cmath>
> 
> #define I_NF 1000000
> 
> const int M =1005;
> 
> int map[666][666];
> int mark[666];
> double d [M];
> 
> 
> double prim(int K)
> {
>      int i,j,n,l;
>      for(i=1;i<=K;i++)
>       d[i]=map[1][i];
>       mark[1]=1;
>       double s=0; //权值
>       for(i=1;i<=K;i++)
>       {
>            double min=I_NF+5;
>            int Record=-5;
>            for(j=1;j<=K;j++)
>            {
>                 if(d[j]<min&&mark[j]==0)
>                 {
>                      min=d[j];
>                      Record=j;
>                 }
>            }
> 
>            if(Record<0)
>             break;
>             s+=min;
>            mark[Record]=1;
>            for(j=1;j<=K;j++)
>            {
>                 if(!mark[j]&&map[Record][j]<d[j])
>                 {
>                      d[j]=map[Record][j];
>                 }
>            }
>       }
>       return s;
> 
> }
> int main()
> {
>     int n;
>     double x[200],y[200],z[200],r[200];
>     while(scanf("%d",&n)&&n!=0){
>             int i,j,k;
>             for(i=1;i<=n;i++){
>                 scanf("%lf%lf%lf%lf",&x[i],&y[i],&z[i],&r[i]);
>             }
>             for(i=1;i<=n;i++){
>                     for(j=1;j<=n;j++){
>                 map[i][j] = (double) (sqrt( pow(x[i]-x[j],2)+pow(y[i]-y[j],2)+pow(z[i]-z[j],2)) - r[i] -r[j]);
>                 if(map[i][j]<0)
>                     map[i][j] = (double)0;
>                     }
>             }
> 
> 
> 
> 
> 
>     printf("%.3lf\n",prim(n));
>     }
>     return 0;
> }

原来是 mark【】标记数组忘记初始化了，坑的死