POJ 1269 Intersecting Lines 直线相交判断

5
0 0 4 4 0 4 4 0
5 0 7 6 1 0 2 3
5 0 7 6 3 -6 4 -3
2 0 2 27 1 5 18 5
0 3 4 0 1 2 2 5

INTERSECTING LINES OUTPUT
POINT 2.00 2.00
NONE
LINE
POINT 2.00 5.00
POINT 1.07 2.20
END OF OUTPUT







输出要用 .2f
坑啊
ACcode：
#include <cstdio>
#include <cmath>
#define eps 1e-8
int sgn(double x){
    if(fabs(x)<eps)return 0;
    if(x<0)return -1;
    return 1;
}
struct Point{
    double x,y;
    Point(){};
    Point(double _x,double _y){
        x=_x;
        y=_y;
    }
    bool operator == (Point b)const{
        return sgn(x-b.x)==0&&sgn(y-b.y)==0;
    }
    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;
    }
    bool parallel(Line v){
        return sgn((e-s)^(v.e-v.s))==0;
    }
    int relation(Point p){
        int c=sgn((p-s)^(e-s));
        if(c<0)return 1;
        if(c>0)return 2;
        return 3;
    }
    int linecrossline(Line v){
        if((*this).parallel(v))
            return v.relation(s)==3;
        return 2;
    }
    Point crosspoint(Line v){
        double a1 = (v.e-v.s)^(s-v.s);
        double a2 = (v.e-v.s)^(e-v.s);
        return Point((s.x*a2-e.x*a1)/(a2-a1),(s.y*a2-e.y*a1)/(a2-a1));
    }
};
int main(){
    int n;
    while(~scanf("%d",&n)){
        puts("INTERSECTING LINES OUTPUT");
        while(n--){
            double x1,x2,x3,x4,y1,y2,y3,y4;
            scanf("%lf%lf%lf%lf%lf%lf%lf%lf",&x1,&y1,&x2,&y2,&x3,&y3,&x4,&y4);
            Line a(Point(x1,y1),Point(x2,y2)),b(Point(x3,y3),Point(x4,y4));
            int flag=a.linecrossline(b);
            if(flag==0){
                puts("NONE");
            }
            else if(flag==1){
                puts("LINE");
            }
            else if(flag==2){
                Point tmp=a.crosspoint(b);
                printf("POINT %.2f %.2f\n",tmp.x,tmp.y);
            }
        }
        puts("END OF OUTPUT");
    }
    return 0;
}