1 #include <iostream>
 2 #include <iomanip>
 3 using namespace std;
 4 struct point { double x, y; };
 5 point bcenter(point pnt[], int n){
 6     point p, s;
 7     double tp, area = 0, tpx = 0, tpy = 0;
 8     p.x = pnt[0].x; p.y = pnt[0].y;
 9     for (int i = 1; i <= n; ++i) { // point: 0 ~ n-1
10         s.x = pnt[(i == n) ? 0 : i].x;
11         s.y = pnt[(i == n) ? 0 : i].y;
12         tp = (p.x * s.y - s.x * p.y); area += tp / 2;
13         tpx += (p.x + s.x) * tp; tpy += (p.y + s.y) * tp;
14         p.x = s.x; p.y = s.y;
15     }
16     s.x = tpx / (6 * area); s.y = tpy / (6 * area);
17     return s;
18 }
19 point P[1000000];
20 int main()
21 {
22     int T,N;
23     cin>>T;
24     cout<<setiosflags(ios::fixed)<<setprecision(2);
25     while(T--){
26         cin>>N;
27         for(int i=0;i<N;i++)    //从0开始输入多边形的n个点 
28             cin>>P[i].x>>P[i].y;
29         point t = bcenter(P,N);    //返回重心坐标 
30         cout<<t.x<<‘ ‘<<t.y<<endl;
31     }
32     return 0;
33 }