func_code_string: #include <bits/stdc++.h>   using namespace std;   const double eps = 1e-8;   const int N = 505;   int sign(double x) { return (x > eps) - (x < -eps); }   int n;   struct P {     double x, y;     P(double a = 0., double b = 0.) : x(a), y(b) {}     P operator+(const P& a) const { return P(x + a.x, y + a.y); }     P operator-(const P& a) const { return P(x - a.x, y - a.y); }     double operator*(const P& a) const { return x * a.x + y * a.y; }     double operator^(const P& a) const { return x * a.y - y * a.x; }     double cross(P a, P b) { return (a - *this) ^ (b - *this); }     double radio(P p, P b) {       if (sign(b.x - x)) return (p.x - x) / (b.x - x);       return (p.y - y) / (b.y - y);     }     void in() { scanf( %lf%lf , &x, &y); }   };   struct PLOY {     int pnt;     P ch[6];     bool anti() {       int dr = sign(ch[0].cross(ch[1], ch[2]));       if (dr == 0) return false;       if (dr < 0) reverse(ch, ch + pnt);       ch[pnt] = ch[0];       return true;     }     double S() {       double s = 0.;       for (int i = 0; i < pnt; i++) s += ch[i] ^ ch[i + 1];       return fabs(s) * 0.5;     }   } pl[505];   pair<double, int> pr[2005];   double cover[505];   double get() {     for (int i = 0; i < N; i++) cover[i] = 0.;     double s = 0.;     int cnt = 0;     for (int i = 0; i < n; i++) {       for (int x = 0; x < pl[i].pnt; x++) {         cnt = 0;         pr[cnt++] = make_pair(0., 0);         pr[cnt++] = make_pair(1., 0);         for (int j = 0; j < n; j++) {           for (int y = 0; y < pl[j].pnt; y++) {             int dr1 = sign(pl[i].ch[x].cross(pl[i].ch[x + 1], pl[j].ch[y]));             int dr2 = sign(pl[i].ch[x].cross(pl[i].ch[x + 1], pl[j].ch[y + 1]));             if (dr1 == 0 && dr2 == 0) {               if (i > j && (pl[i].ch[x + 1] - pl[i].ch[x]) *                                    (pl[j].ch[y + 1] - pl[j].ch[y]) >                                0.) {                 pr[cnt++] =                     make_pair(pl[i].ch[x].radio(pl[j].ch[y], pl[i].ch[x + 1]), 1);                 pr[cnt++] = make_pair(                     pl[i].ch[x].radio(pl[j].ch[y + 1], pl[i].ch[x + 1]), -1);               }             } else if (dr1 >= 0 && dr2 < 0) {               double s1 = pl[j].ch[y + 1].cross(pl[j].ch[y], pl[i].ch[x]);               double s2 = pl[j].ch[y + 1].cross(pl[j].ch[y], pl[i].ch[x + 1]);               pr[cnt++] = make_pair(s1 / (s1 - s2), 1);             } else if (dr2 >= 0 && dr1 < 0) {               double s1 = pl[j].ch[y].cross(pl[j].ch[y + 1], pl[i].ch[x]);               double s2 = pl[j].ch[y].cross(pl[j].ch[y + 1], pl[i].ch[x + 1]);               pr[cnt++] = make_pair(s1 / (s1 - s2), -1);             }           }         }         sort(pr, pr + cnt);         double r = 0., cur, last;         int sum;         sum = pr[0].second;         last = min(max(pr[0].first, 0.), 1.);         for (int k = 1; k < cnt; k++) {           cur = min(max(pr[k].first, 0.), 1.);           cover[sum] += (cur - last) * (pl[i].ch[x] ^ pl[i].ch[x + 1]);           sum += pr[k].second, last = cur;         }       }     }     return cover[0] * 0.5;   }   int main() {     while (~scanf( %d , &n)) {       double ans = 0.;       for (int i = 0; i < n; i++) {         for (int j = 0; j < 4; j++) pl[i].ch[j].in();         pl[i].pnt = 4;         if (!pl[i].anti()) continue;         ans += pl[i].S();       }       printf( %.10f n , ans / get());     }     return 0;   }   