UVA 10652 凸包问题

#include <cstdio>
#include <cstring>
#include <algorithm>
#include <cmath>
#include <iostream>
using namespace std;

const double eps = 1e-10;
const int N = 610;
int dcmp(double x)
{
    if(abs(x) < eps) return 0;
    if(x < 0) return -1;
    else return 1;
}

struct Point{
    double x,y;
    Point(double x = 0,double y = 0):x(x),y(y){}
    bool operator<(const Point &m)const{
        return dcmp(x - m.x) < 0 || (dcmp(x - m.x) == 0 && dcmp(y - m.y) < 0);
    }

    bool operator==(const Point &m)const{
        return dcmp(x - m.x) == 0 && dcmp(y - m.y) == 0;
    }
};

Point ch[N<<2],p[N<<2];

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 = 0;
    for(int i=1;i<n-1;i++){
        area += Cross(p[i] - p[0] , p[i+1] - p[0]);
    }
    return area / 2;
}
//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 = 0;
    for(int i = 0; i < n; i++)
    {
        while(m > 1 && Cross(ch[m-1]-ch[m-2], p[i]-ch[m-2]) <= 0) m--;
        ch[m++] = p[i];
    }
    int k = m;
    for(int i = n-2; i >= 0; i--)
    {
        while(m > k && Cross(ch[m-1]-ch[m-2], p[i]-ch[m-2]) <= 0) m--;
        ch[m++] = p[i];
    }
    if(n > 1) 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=0;
        double area = 0;
        for(int i=0;i<n;i++)
        {
            scanf("%lf%lf%lf%lf%lf",&x,&y,&w,&h,&_angle);
            area += w*h;
            double rad = -_angle * acos(-1) / 180;
            Point o(x,y);
            //cout<<"  rad:  "<<rad<<endl;
            p[k++] = GetReverse(Vector(-w/2 , h/2),rad) + o;
            p[k++] = GetReverse(Vector(w/2 , h/2),rad) + o;
            p[k++] = GetReverse(Vector(w/2 , -h/2),rad) + o;
            p[k++] = GetReverse(Vector(-w/2 , -h/2),rad) + o;
        }

        int m = ConvexHull(p , k , ch);
        double sumOfArea = ConvexPolygonArea(ch , m);
        double ans = area / sumOfArea * 100;

        printf("%.1f %%
",ans);
    }
    return 0;
}