uva 11437

计算几何；

直线交点；

#include<cstdio>
using namespace std;

struct node
{
    double x,y;
    node(double x=0,double y=0):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)/3;
        e=c+(a-c)/3;
        f=a+(b-a)/3;
        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
",cross(q-p,r-p)/2);
    }
    return 0;
}