又遇到一个奇葩问题....输出double用%f...

题目链接：http://openoj.awaysoft.com:8080/judge/contest/view.action?cid=384#problem/D

#include <stdio.h>
#include <string.h>
#include <math.h>
double f[110][110];
int vist[110];
struct node
{
    double x,y,z,r;
}p[110];
double ff(node a,node b)
{
    return (sqrt((a.x-b.x)*(a.x-b.x)+(a.y-b.y)*(a.y-b.y)+(a.z-b.z)*(a.z-b.z))-a.r-b.r);
}
int main()
{
    int n,i,j;
    while (~scanf("%d",&n) && n)
    {
        for (i=1;i<=n;i++)
            scanf("%lf%lf%lf%lf",&p[i].x,&p[i].y,&p[i].z,&p[i].r);
        for (i=1;i<n;i++)
            for (j=i+1;j<=n;j++)
            {
                double l=ff(p[i],p[j]);
                if (l>0) f[i][j]=f[j][i]=l;
                    else f[i][j]=f[j][i]=0.000;        
            }
        memset(vist,0,sizeof(vist));
        vist[1]=1;
        int pos,t=n-1;
        double s=0;
        while (t--)
        {
            double min=110.000;
            for (i=2;i<=n;i++)
                if (!vist[i] && f[1][i]<min)
                {
                    pos=i;
                    min=f[1][i];
                }
            if (min-110.000==0) break;
            s+=min;
            vist[pos]=1;
            for (i=2;i<=n;i++)
                if (!vist[i] && f[pos][i]<f[1][i])
                    f[1][i]=f[pos][i];
        }
        printf("%0.3f\n",s);
    }
    return 0;
}