计算几何基础模板

#include<cstdio>
#include<cstring>
#include<algorithm>
#include<cstdlib>
#include<cmath>
#include<iostream>
#define eps 1e-8
using namespace std;
typedef long long ll;
int sgn(double x){
    if(fabs(x)<eps) return 0;
    else if(x<0) return -1;
    else return 1;
}
struct Point{
    double x,y;
    Point(){}
    Point(double _x,double _y){x=_x;y=_y;}
    Point operator-(const Point &b)const{return Point(x-b.x,y-b.y);}
    double operator^(const Point &b)const{return x*b.y-y*b.x;}
    double operator*(const Point &b)const{return x*b.x+y*b.y;}
};
struct Line{
    Point s,e;
    Line(){}
    Line(Point _s,Point _e){s=_s,e=_e;}
    pair<int,Point>operator&(const Line &b)const{
        Point res=s;
        if(sgn((s-e)^(b.s-b.e))==0){
            if(sgn((s-b.e)^(b.s-b.e))==0) return make_pair(0,res);
            else return make_pair(1,res);
        }
        double t=((s-b.s)^(b.s-b.e))/((s-e)^(b.s-b.e));
        res.x+=(e.x-s.x)*t;
        res.y+=(e.y-s.y)*t;
        return make_pair(2,res);
    }
};
bool inter(Line l1,Line l2){
    return 
    max(l1.s.x,l1.e.x)>=min(l2.s.x,l2.e.x)&&
    max(l2.s.x,l2.e.x)>=min(l1.s.x,l1.e.x)&&
    max(l1.s.y,l1.e.y)>=min(l2.s.y,l2.e.y)&&
    max(l2.s.y,l2.e.y)>=min(l1.s.y,l1.e.y)&&
    sgn((l2.s-l1.e)^(l1.s-l1.e))*sgn((l2.e-l1.e)^(l1.s-l1.e))<=0&&
    sgn((l1.s-l2.e)^(l2.s-l2.e))*sgn((l1.e-l2.e)^(l2.s-l2.e))<=0;
}

int main(){
    return 0;
}