如果是个圆的话好办，如果是拉成椭圆呢？直接压回去！！！
然后随机增量法就行了
CODE:
#include<cstdio>
#include<iostream>
#include<cstring>
#include<algorithm>
#include<cmath>
using namespace std;
#define sqr(x) ((x)*(x))
#define fi first
#define se second
#define maxn 100100
typedef pair<double,double> ii;
ii a[maxn],cir;
double r;
double dis(ii x,ii y) {
return sqrt(sqr(x.fi-y.fi)+sqr(x.se-y.se));
}
ii getcir(ii x,ii y,ii z){
double a=sqr(x.fi)-sqr(y.fi)+sqr(x.se)-sqr(y.se),
b=sqr(x.fi)-sqr(z.fi)+sqr(x.se)-sqr(z.se),
c=2*(x.se-z.se)*(x.fi-y.fi)-2*(x.se-y.se)*(x.fi-z.fi);
return ii((a*(x.se-z.se)-b*(x.se-y.se))/c,
(a*(x.fi-z.fi)-b*(x.fi-y.fi))/(-c));
}
#define exp 1e-10
int cmp(double x) {
if (x<-exp) return -1;
if (x>exp) return 1;
return 0;
}
int n;
const double pi=acos(-1);
int main(){
freopen("amplifier.in","r",stdin);
freopen("amplifier.out","w",stdout);
scanf("%d",&n);
for (int i=1;i<=n;i++) scanf("%lf%lf",&a[i].fi,&a[i].se);
double tmp;
scanf("%lf",&tmp);
tmp*=-pi/180;
for (int i=1;i<=n;i++) a[i]=ii(a[i].fi*cos(tmp)-a[i].se*sin(tmp),
a[i].fi*sin(tmp)+a[i].se*cos(tmp));
scanf("%lf",&tmp);
for (int i=1;i<=n;i++) a[i].fi/=tmp;
random_shuffle(a+1,a+1+n);
cir=a[1],r=0;
for (int i=1;i<=n;i++) {
if (cmp(dis(cir,a[i])-r)<=0) continue;
cir=a[i],r=0;
for (int j=1;j<i;j++) {
if (cmp(dis(cir,a[j])-r)<=0) continue;
cir.fi=(a[i].fi+a[j].fi)/2,cir.se=(a[i].se+a[j].se)/2;
r=dis(cir,a[j]);
for (int k=1;k<j;k++) {
if (cmp(dis(cir,a[k])-r)<=0) continue;
cir=getcir(a[i],a[j],a[k]);
r=dis(cir,a[i]);
}
}
}
printf("%.3lf ",r);
return 0;
}