题目描述：

题解：

这道题告诉我们POJ的数据是极强的……

计算几何。

有好几个特殊情况，都在这组数据里面。

106259 2664 8292 9080 1244 2972 9097 96800 1 1 01 0 2 10 1 2 11 0 1 20 0 10 100 0 9 80 0 10 100 0 8 90.9 3.1 4 00 3 2 20 0 0 20 0 -3 21 1 1 40 0 2 31 2 1 40 0 2 30 0 1 10 0 1 2

感谢，

代码：

#include
      
       #include
       
        #include
        
         #include
         
          using namespace std;const double eps = 1e-8;int dcmp(double x){    if(fabs(x)<=eps)return 0;    return x>0?1:-1;}struct Point{    double x,y;    Point(){}    Point(double x,double y):x(x),y(y){}    Point operator + (const Point&a)const{
    return Point(x+a.x,y+a.y);}    Point operator - (const Point&a)const{
    return Point(x-a.x,y-a.y);}    Point operator * (const double&a)const{
    return Point(x*a,y*a);}    double operator ^ (const Point&a)const{
    return x*a.y-y*a.x;}}a,b,c,d;typedef Point Vector;struct Line{    Point p;    Vector v;    Line(){}    Line(Point p,Vector v):p(p),v(v){}}s,t;int n;bool diff(Line l,Point a,Point b){    return dcmp(l.v^(a-l.p))*(l.v^(b-l.p))<=0;}Point L_L(Line a,Line b){    double t = ((b.p-a.p)^b.v)/(a.v^b.v);    return a.p+a.v*t;}Point L_Y(Line a,double y){    return a.p+a.v*((y-a.p.y)/a.v.y);}void work(){    scanf("%lf%lf%lf%lf%lf%lf%lf%lf",&a.x,&a.y,&b.x,&b.y,&c.x,&c.y,&d.x,&d.y);    if(a.y