POJ 2653 Pick-up sticks

[計算幾何:叉積]
原本以為直接爆會超時ㄎㄎ

#include<cmath>
#include<algorithm>
#include<stdio.h>
#include<vector>
#include<cstring>
#define MAX 100000
#define EPS 1E-8
using namespace std;
class Point
{
public:
    double x,y;
    Point(){}
    Point(double _x,double _y) : x(_x),y(_y){}
};
class Segment
{
public:
    Point aa,bb;
    Segment(){}
    Segment(Point _aa,Point _bb): aa(_aa),bb(_bb){}
};
double GetCrossMult(const Point _A,const  Point _B,const Point _O)
{
    return (_A.x-_O.x)*(_B.y-_O.y)-(_B.x-_O.x)*(_A.y-_O.y);
}
bool IsIntersect(Segment sg1,Segment sg2)
{
    return (GetCrossMult(sg2.aa, sg2.bb, sg1.aa)*GetCrossMult(sg2.aa, sg2.bb, sg1.bb)<EPS)&&
                (GetCrossMult(sg1.aa, sg1.bb, sg2.aa)*GetCrossMult(sg1.aa, sg1.bb, sg2.bb)<EPS);
}
Segment Sgs[MAX];
int Sgscnt;
int main()
{
    vector<int> tmp;
    while(scanf("%d",&Sgscnt)&&Sgscnt)
    {
        tmp.clear();
        for(int lx=0;lx<Sgscnt;lx++)
            scanf("%lf %lf %lf %lf",&Sgs[lx].aa.x,&Sgs[lx].aa.y,&Sgs[lx].bb.x,&Sgs[lx].bb.y);
        for(int lx=0;lx<Sgscnt;lx++)
        {
            bool IsCross=false;
            for(int ly=lx+1;ly<Sgscnt&&!IsCross;ly++)
                IsCross=IsIntersect(Sgs[lx],Sgs[ly]);
            if(IsCross==false)
                tmp.push_back(lx);
        }
        printf("Top sticks:");
        for(int lx=0;lx<tmp.size();lx++)
            printf(" %d%c",tmp[lx]+1,((lx==tmp.size()-1) ? '.':','));
        printf("\n");
    }
    return 0;
}