UVA 10652 凸包问题

 #include <cstdio>
 #include <cstring>
 #include <algorithm>
 #include <cmath>
 #include <iostream>
 using namespace std;
 
 const double eps = 1e-;
 const int N = ;
 int dcmp(double x)
 {
     if(abs(x) < eps) return ;
     if(x < ) return -;
     else return ;
 }
 
 struct Point{
     double x,y;
     Point(double x = ,double y = ):x(x),y(y){}
     bool operator<(const Point &m)const{
         return dcmp(x - m.x) <  || (dcmp(x - m.x) ==  && dcmp(y - m.y) < );
     }
 
     bool operator==(const Point &m)const{
         return dcmp(x - m.x) ==  && dcmp(y - m.y) == ;
     }
 };
 
 Point ch[N<<],p[N<<];
 
 typedef Point Vector;
 
 Vector operator+(Vector a , Vector b)
 {
     return Vector(a.x + b.x , a.y + b.y);
 }
 
 Vector operator-(Point a , Point b)
 {
     return Vector(a.x - b.x , a.y - b.y);
 }
 
 Vector operator*(Vector a , double b)
 {
     return Vector(a.x * b , a.y * b);
 }
 
 Vector operator/(Vector a , double b)
 {
     return Vector(a.x / b , a.y/b);
 }
 
 double Cross(Vector a , Vector b)
 {
     return a.x * b.y - a.y * b.x;
 }
 
 Vector GetReverse(Vector a , double rad)
 {
     double x = a.x * cos(rad) - a.y * sin(rad);
     double y = a.x * sin(rad) + a.y * cos(rad);
     return Vector(x,y);
 }
 //计算多边形面积
 double ConvexPolygonArea(Point *p , int n)
 {
     double area = ;
     for(int i=;i<n-;i++){
         area += Cross(p[i] - p[] , p[i+] - p[]);
     }
     return area / ;
 }
 //求形成凸包的最大范围
 int ConvexHull(Point *p, int n, Point *ch) //凸包
 {
     sort(p, p+n);
     n = unique(p, p+n) - p; //去重
     int m = ;
     for(int i = ; i < n; i++)
     {
         while(m >  && Cross(ch[m-]-ch[m-], p[i]-ch[m-]) <= ) m--;
         ch[m++] = p[i];
     }
     int k = m;
     for(int i = n-; i >= ; i--)
     {
         while(m > k && Cross(ch[m-]-ch[m-], p[i]-ch[m-]) <= ) m--;
         ch[m++] = p[i];
     }
     if(n > ) m--;
     return m;
 }
 int main()
 {
   //  freopen("test.in","rb",stdin);
 
     int T,n;
     double x,y,w,h,_angle; //_angle表示度数，自己还要转化成弧度
     scanf("%d",&T);
     while(T--){
         scanf("%d",&n);
         int k=;
         double area = ;
         for(int i=;i<n;i++)
         {
             scanf("%lf%lf%lf%lf%lf",&x,&y,&w,&h,&_angle);
             area += w*h;
             double rad = -_angle * acos(-) / ;
             Point o(x,y);
             //cout<<"  rad:  "<<rad<<endl;
             p[k++] = GetReverse(Vector(-w/ , h/),rad) + o;
             p[k++] = GetReverse(Vector(w/ , h/),rad) + o;
             p[k++] = GetReverse(Vector(w/ , -h/),rad) + o;
             p[k++] = GetReverse(Vector(-w/ , -h/),rad) + o;
         }
 
         int m = ConvexHull(p , k , ch);
         double sumOfArea = ConvexPolygonArea(ch , m);
         double ans = area / sumOfArea * ;
 
         printf("%.1f %%\n",ans);
     }
     return ;
 }