【2011 Greater New York Regional 】Problem G: Rancher's Gift

计算几何的题目，很简单；

自己随手敲了个，纪念下！

 #include<cstdio>
 #include<cmath>
 using namespace std;

 struct point
 {
     double x,y;
     point(double x=,double y=):x(x),y(y) { }
 } a,b,c,d;

 point midd(point a,point b)
 {
     return point((a.x+b.x)/2.0,(a.y+b.y)/2.0);
 }
 point operator + (point a,point b)
 {
     return point(a.x+b.x,a.y+b.y);
 }
 point operator - (point a,point b)
 {
     return point(a.x-b.x,a.y-b.y);
 }
 point operator * (point a,double p)
 {
     return point(a.x*p,a.y*p);
 }
 point operator / (point b,double p)
 {
     return point(a.x/p,a.y/p);
 }
 double cross(point a,point b)
 {
     return a.x*b.y-b.x*a.y;
 }
 point getlineintersection(point p,point v,point q,point w)
 {
     point u=p-q;
     double t=cross(w,u)/cross(v,w);
     return p+v*t;
 }
 double area(point a,point b,point c)
 {
     return cross(b-a,c-a)/2.0;
 }
 double dis(point a,point b)
 {
     return sqrt((a.x-b.x)*(a.x-b.x)+(a.y-b.y)*(a.y-b.y));
 }
 double line(point a,point b,point c,point d)
 {
     return dis(a,b)+dis(b,c)+dis(c,d)+dis(d,a);
 }

 int main()
 {
     int t,ca;
     scanf("%d",&t);
     while(t--)
     {
         scanf("%d",&ca);
         printf("%d ",ca);
         a.x=0.0,a.y=0.0,b.y=0.0;
         scanf("%lf%lf%lf%lf%lf",&b.x,&c.x,&c.y,&d.x,&d.y);
         point dd=midd(a,b);
         point aa=midd(b,c);
         point cc=midd(a,d);
         point bb=midd(c,d);
         point aaa=getlineintersection(d,d-dd,a,a-aa);
         point bbb=getlineintersection(a,aa-a,b,bb-b);
         point ccc=getlineintersection(c,cc-c,b,bb-b);
         point ddd=getlineintersection(c,cc-c,d,dd-d);
         printf("%.3lf ",area(a,b,bbb)/160.0);
         printf("%.3lf ",area(b,c,ccc)/160.0);
         printf("%.3lf ",area(c,d,ddd)/160.0);
         printf("%.3lf ",area(d,a,aaa)/160.0);
         printf("%.3lf ",((area(ddd,aaa,bbb)+area(bbb,ccc,ddd))/160.0));
         printf("%.0lf\n",ceil(line(aaa,bbb,ccc,ddd)*16.5));
     }
     return ;
 }