这是一道简单的计算几何；

 

In the picture below you can see a triangle ABC. Point D, E and F divides the sides BC, CA and AB into ratio 1:2 respectively. That is CD=2BD, AE=2CE and BF=2AF. A, D; B, E and C, F are connected. AD and BE intersects at P, BE and CF intersects at Q and CF and AD intersects at R.

So now a new triangle PQR is formed. Given triangle ABC your job is to find the area of triangle PQR.

 这是我在uva上做的第一道题，纪念一下 =_=

 

#include
    
     using namespace std;typedef struct points{    double x,y;    points(double xx=0,double yy=0):x(xx),y(yy){}}vectors;points operator + (points a,vectors b){    return points(a.x+b.x,a.y+b.y);}vectors operator - (points a,points b){    return vectors(a.x-b.x,a.y-b.y);}vectors operator * (double a,vectors b){    return vectors(a*b.x,a*b.y);}double cross(vectors a,vectors b){    return a.x*b.y-a.y*b.x;}points inter(points a,points b,points c,points d){    vectors v=b-a,w=d-c,u=a-c;    double t=cross(w,u)/cross(v,w);    return a+t*v;}int main(){    points a,b,c,d,e,f,p,q,r;    int n,area;    cin>>n;    while(n--)    {        cin>>a.x>>a.y>>b.x>>b.y>>c.x>>c.y;        d=b+1/3.0*(c-b);        e=c+1/3.0*(a-c);        f=a+1/3.0*(b-a);        p=inter(a,d,b,e);        q=inter(b,e,c,f);        r=inter(c,f,a,d);        area=(int)(0.5+cross(q-p,r-p)/2);        cout<
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