1 struct Point{
 2     double x, y;
 3     int id;
 4 } P[55], Min;
 5
 6 double dmult(Point p1, Point p2, Point p)
 7 {
 8     return (p1.x-p.x)*(p2.x-p.x)+(p1.y-p.y)*(p2.y-p.y);
 9 }
10
11 double Distance(Point a, Point b)
12 {
13     return sqrt((b.x-a.x)*(b.x-a.x)+(b.y-a.y)*(b.y-a.y));
14 }
15
16 int T;
17 int n;
18 bool vis[55];
19
20 void Solve()
21 {
22     scanf("%d", &T);
23     while(T--)
24     {
25         memset(vis, true, sizeof(vis));
26         scanf("%d", &n);
27         Min = (Point){INF, INF, INF};
28         for(int i = 1; i <= n; ++i)
29         {
30             scanf("%d%lf%lf", &P[i].id, &P[i].x, &P[i].y);
31             if(P[i].y < Min.y)
32             {
33                 Min = P[i];
34             }
35         }
36
37         vis[Min.id] = false;
38         Point Q = (Point){0, Min.y};
39         Point H = Min;
40
41         printf("%d %d ", n, Min.id);
42         for(int i = 2; i <= n; ++i)
43         {
44             double Min_a = INF;
45             for(int j = 1; j <= n; ++j)
46             {
47                 if(vis[P[j].id] == false) continue;
48                 Point t;
49                 t.x = P[j].x-(H.x-Q.x);
50                 t.y = P[j].y-(H.y-Q.y);
51                 double x = dmult(t, H, Q);
52                 double a = acos(x/Distance(Q, H)/Distance(Q, t));
53                 if(a < Min_a)
54                 {
55                     Min_a = a;
56                     Min = P[j];
57                 }
58             }
59             vis[Min.id] = false;
60             Q = H;
61             H = Min;
62             printf("%d", Min.id);
63             printf("%s", i==n?"\n":" ");
64         }
65     }
66 }