Can someone help me?
#include<iostream>
#include<cstring>
#include<algorithm>
#include<cmath>
using namespace std;
struct Tpoint{
double x,y;
};
const double eps=1e-8;
const double inf=2147483647.0;
int n;
Tpoint p[6000];
int id[6000];
int dcmp(double x){
return x<-eps?-1:x>eps;
}
double cross(Tpoint p0,Tpoint p1,Tpoint p2){
double x1=p1.x-p0.x;
double x2=p2.x-p0.x;
double y1=p1.y-p0.y;
double y2=p2.y-p0.y;
return x1*y2-x2*y1;
}
double dot(Tpoint p0,Tpoint p1,Tpoint p2){
double x1=p1.x-p0.x;
double x2=p2.x-p0.x;
double y1=p1.y-p0.y;
double y2=p2.y-p0.y;
return x1*x2+y1*y2;
}
double angle(Tpoint p0,Tpoint p1,Tpoint p2){
double cr=cross(p0,p1,p2);
double dt=dot(p0,p1,p2);
if(!dcmp(cr)) cr=0.0;
if(!dcmp(dt)) dt=0.0;
return atan2(cr,dt);
}
bool cmp(const Tpoint& a,const Tpoint &b){
return dcmp(atan2(a.y-p[0].y,a.x-p[0].x)-atan2(b.y-p[0].y,b.x-p[0].x))<0;
}
bool cmp2(const int &a,const int &b){
return dcmp(angle(p[a],p[0],p[1])-angle(p[b],p[0],p[1]))<0;
}
void init(){
Tpoint tp;
int i,j;
double minx,miny;
cin>>n;
for(i=0;i<n;i++) cin>>p[i].x>>p[i].y;
for(minx=miny=inf,i=0;i<n;i++)
if(dcmp(p[i].x-minx)<0 || (dcmp(p[i].x-minx)==0 && dcmp(p[i].y-miny)<0)){
minx=p[i].x;
miny=p[i].y;
j=i;
}
tp=p[j];
p[j]=p[0];
p[0]=tp;
sort(p+1,p+n,cmp);
}
void solve(){
int i;
for(i=0;i<n;i++) id[i]=i;
sort(id+2,id+n,cmp2);
cout<<p[0].x<<" "<<p[0].y<<endl;
cout<<p[1].x<<" "<<p[1].y<<endl;
//for(i=2;i<n;i++) cout<<p[id[i]].x<<" "<<p[id[i]].y<<" "<<angle(p[id[i]],p[0],p[1])<<endl;
cout<<p[id[n/2+1]].x<<" "<<p[id[n/2+1]].y<<endl;
}
int main(){
init();
solve();
return 0;
}
