先把已有的边并查集了，然后MST即可
记得开double
#include<iostream>
#include<cstdio>
#include<algorithm>
#include<cmath>
using namespace std;
const int N=1005;
int n,m,f[N],con,tot;
double x[N],y[N],ans;
struct qwe
{
int u,v;
double w;
}e[N*N];
bool cmp(const qwe &a,const qwe &b)
{
return a.w<b.w;
}
int read()
{
int r=0,f=1;
char p=getchar();
while(p>'9'||p<'0')
{
if(p=='-')
f=-1;
p=getchar();
}
while(p>='0'&&p<='9')
{
r=r*10+p-48;
p=getchar();
}
return r*f;
}
inline int zhao(int x)
{
return f[x]==x?x:f[x]=zhao(f[x]);
}
int main()
{
n=read(),m=read();
for(int i=1;i<=n;i++)
x[i]=read(),y[i]=read(),f[i]=i;
for(int i=1;i<=m;i++)
{
int x=read(),y=read(),fx=zhao(x),fy=zhao(y);
if(fx!=fy)
con++,f[fx]=fy;
}
for(int i=1;i<=n;i++)
for(int j=i+1;j<=n;j++)
if(zhao(i)!=zhao(j))
e[++tot]=(qwe){i,j,sqrt(abs(x[i]-x[j])*abs(x[i]-x[j])+abs(y[i]-y[j])*abs(y[i]-y[j]))};
sort(e+1,e+1+tot,cmp);
for(int i=1;i<=tot&&con<n-1;i++)
{
int fu=zhao(e[i].u),fv=zhao(e[i].v);
if(fu!=fv)
con++,ans+=e[i].w,f[fu]=fv;
}
printf("%.2lf",ans);
return 0;
}