uva 11437 - Triangle Fun

计算几何；

直线交点；

 #include<cstdio>
 using namespace std;

 struct node
 {
     double x,y;
     node(double x=,double y=):x(x),y(y){ }
 }a,b,c,d,e,f,p,q,r;
 node operator-(node u,node v){return node(u.x-v.x,u.y-v.y);}
 node operator+(node u,node v){return node(u.x+v.x,u.y+v.y);}
 node operator*(node u,double v){return node(u.x*v,u.y*v);}
 node operator/(node u,double v){return node(u.x/v,u.y/v);}

 double cross(node u,node v)
 {
     return u.x*v.y-u.y*v.x;
 }

 node get(node p,node v,node q,node w)
 {
     node u=p-q;
     double t=cross(w,u)/cross(v,w);
     return p+v*t;
 }

 int main()
 {
     int n;
     scanf("%d",&n);
     while(n--)
     {
         scanf("%lf%lf",&a.x,&a.y);
         scanf("%lf%lf",&b.x,&b.y);
         scanf("%lf%lf",&c.x,&c.y);
         d=b+(c-b)/;
         e=c+(a-c)/;
         f=a+(b-a)/;
         p=get(b,e-b,a,d-a);
         q=get(c,f-c,b,e-b);
         r=get(c,f-c,d,a-d);
         printf("%.0lf\n",cross(q-p,r-p)/);
     }
     return ;
 }