hud 1785 畅通工程

#include<iostream>
#include<stdio.h>
#include<algorithm>
#include<math.h>
using namespace std;
int par[103];
struct Island
{
    int x,y;
} isl[103];
struct Node
{
    int isl1,isl2;
    double dis;
} rode[100*99/2];
int find(int a)
{
    if(a!=par[a])
    {
        par[a]=find(par[a]);
    }
    return par[a];
}
void build(int a,int b)
{
    int fa=find(a);
    int fb=find(b);
    if(fa!=fb)
    {
        par[fb]=fa;
    }
}
bool cmp(Node a,Node b)
{
    return a.dis<b.dis;
}
int main()
{
    int t;
    scanf("%d",&t);
    while(t--)
    {
        int c;
        scanf("%d",&c);
        if(c == 1 || c == 0) {printf("oh!\n"); continue;}
        for(int i=0; i<c; i++)
            par[i]=i;
        int num=c*(c-1)/2;
        for(int i=0; i<c; i++)
        {
            scanf("%d%d",&isl[i].x,&isl[i].y);
        }
        int t=0;
        for(int i=0; i<c; i++)
        {
            for(int j=i+1; j<c; j++)
            {
                double mid=double((isl[i].x-isl[j].x)*(isl[i].x-isl[j].x)+(isl[i].y-isl[j].y)*(isl[i].y-isl[j].y));
                if(mid<100||mid>1000000) continue;
                else
                {
                    rode[t].isl1=i;
                    rode[t].isl2=j;
                    rode[t].dis=sqrt(mid);
                    t++;
                }
            }
        }
        //cout<<t<<"  num  " <<num;
        double ans=0.0;
        int cnt=0;
        sort(rode,rode+t,cmp);
        for(int i=0;i<t;i++)
        {
            if(find(rode[i].isl1)!=find(rode[i].isl2))
            {
                ans+=rode[i].dis;
                build(rode[i].isl1,rode[i].isl2);
                cnt++;
            }
        }
        ans*=100;
        if(cnt!=c-1)  printf("oh!\n");
        else printf("%.1lf\n",ans);
    }
    return 0;
}