SortareUnghi

#include <fstream>
#include <algorithm>
using namespace std;
ifstream f("sortareunghi.in");
ofstream g("sortareunghi.out");
pair<int,int> v[101];
int n,i;

int cadran(int x,int y)
{
    if(x>0&&y>=0)
        return 1;
    if(x<=0&&y>0)
        return 2;
    if(x<=0&&y<=0)
        return 3;
    return 4;
}

int det(int X1,int Y1,int X2,int Y2,int X3,int Y3)
{
    return (X2-X1)*(Y3-Y1)-(X3-X1)*(Y2-Y1);
}

int cmp(const pair<int,int> &a,const pair<int,int> &b)
{
    int c1=cadran(a.first,a.second);
    int c2=cadran(b.first,b.second);
    if(c1!=c2)
        return c1<c2;
    else
    {
        int d=det(0,0,a.first,a.second,b.first,b.second);
        if (d!=0)
            return d>0;
        else
            return a.first*a.first+a.second*a.second<b.first*b.first+b.second*b.second;
    }
}

int main()
{
    f>>n;
    for (i=1;i<=n;++i)
        f>>v[i].first>>v[i].second;
    sort(v+1,v+n+1,cmp);
    for (i=1;i<=n;++i)
        g<<v[i].first<<' '<<v[i].second<<'\n';
    return 0;
}