Uva 10652 Board Wrapping

二次联通门 : Virtual Judge Uva 10652 Board Wrapping

/*
    Uva 10652 Board Wrapping

    计算几何

    将每个家具拆为4个点

    对所有点求一个凸包
    然后求凸包的面积即可 

    思路不难。。
    但是写起来好麻烦好麻烦

    需要注意的东西有很多

    1. 角度制转弧度制
     2. EPS的选择
    3. PI的取值 (以防万一以后还是都写acos(-1)吧。。。)
    4. 在把家具拆成四个点时的细节
    4. 计算多边形的面积
*/
#include <algorithm>
#include <iostream>
#include <cstdio>
#include <cmath>

#define Max 2500

#define PI 3.1415926535897

#define EPS 1e-8

void read (int &now)
{
    register char word = getchar ();
    for (now = 0; !isdigit (word); word = getchar ());
    for (; isdigit (word); now = now * 10 + word - ‘0‘, word = getchar ());
}

struct Point
{
    double x, y;

    Point (const double &__x, const double &__y) : x (__x), y (__y) {}
    Point () {}

    bool operator < (const Point &now) const
    {
        return this->x == now.x ? this->y < now.y : this->x < now.x;
    }

    bool operator == (const Point &now) const
    {
        return (this->x - now.x < EPS) && (this->y - now.y < EPS);
    }
};
typedef Point Vector;

Vector operator + (const Vector &A, const Vector &B)
{
    return Vector (A.x + B.x, A.y + B.y);
}

Vector operator - (const Vector &A, const Vector &B)
{
    return Vector (A.x - B.x, A.y - B.y);
}

Vector operator * (const Vector &now, const double P)
{
    return Vector (now.x * P, now.y * P);
}

Vector operator / (const Vector &now, const double P)
{
    return Vector (now.x / P, now.y / P);
}

inline double to_rad (double now)
{
    return now / 180 * PI;
}

inline Vector Rotate (Vector A, double rad)
{
    return Vector (A.x * cos (rad) - A.y * sin (rad), A.x * sin (rad) + A.y * cos (rad));
}

inline double Cross (Vector A, Vector B)
{
    return A.x * B.y - A.y * B.x;
}

int Convex_Hull (Point *point, int N, Point *Stack)
{
    std :: sort (point, point + N);
    int top = 0;
    for (int i = 0; i < N; i ++)
    {
        for (; top > 1 && Cross (Stack[top - 1] - Stack[top - 2], point[i] - Stack[top - 2]) <= 0; -- top);
        Stack[top ++] = point[i];
    }

    int k = top;
    for (int i = N - 2; i >= 0; -- i)
    {
        for (; top > k && Cross (Stack[top - 1] - Stack[top - 2], point[i] - Stack[top - 2]) <= 0; -- top);
        Stack[top ++] = point[i];
    }
    if (N > 1)
        -- top;
    return top;

}

double Polygon_Area (Point *point, int N)
{
    double area = 0;
    for (int i = 1; i < N - 1; i ++)
        area += Cross (point[i] - point[0], point[i + 1] - point[0]);
    return area / 2;
}

Point point[Max], Stack[Max];

int main (int argc, char *argv[])
{
    int T, N, M;

    read (T);
    register int i;
    double x, y, w, h, j;
    double angle, _area;

    int cur;
    for (; T; -- T)
    {
        read (N);
        cur = 0, _area = 0;
        for (i = 1; i <= N; ++ i)
        {
            scanf ("%lf%lf%lf%lf%lf", &x, &y, &w, &h, &j);
            Point now (x, y);

            angle = -to_rad (j);
            point[cur ++] = now + Rotate (Vector (-w / 2, -h / 2), angle);
            point[cur ++] = now + Rotate (Vector (w / 2, -h / 2), angle);
            point[cur ++] = now + Rotate (Vector (-w / 2, h / 2), angle);
            point[cur ++] = now + Rotate (Vector (w / 2, h / 2), angle);

            _area += w * h;
        }

        M = Convex_Hull (point, cur, Stack);
        double __area = Polygon_Area (Stack, M);

        printf ("%.1lf %%\n", _area * 100 / __area);
    }
    return 0;
}