1 #include <cstdio>
 2 #include <cmath>
 3 #include <vector>
 4 #include <cstring>
 5 #include <algorithm>
 6 using namespace std;
 7 
 8 const int maxn = 1000 + 5, maxe = 1000 * 1000 / 2 + 5, INF = 0x3f3f3f3f;
 9 int n, m, head[maxn];
10 double Max[maxn][maxn];
11 struct City {
12     int u, v, population;
13 }city[maxn];
14 struct Edge{
15     int u, v, population;
16     double w;
17     bool vis;
18 }edge[maxe];
19 vector <int> G[maxn];
20 
21 bool cmp(const Edge &a, const Edge &b) {
22     return a.w < b.w;
23 }
24 
25 int Find(int x) {
26     if(x == head[x]) return x;
27     else return head[x] = Find(head[x]);
28 }
29 
30 double Distance(int i, int j) {
31     int x1 = city[i].u, y1 = city[i].v,
32         x2 = city[j].u, y2 = city[j].v;
33     return sqrt((double)(x2 - x1) * (x2 - x1) + (double)(y2 - y1) * (y2 - y1));
34 }
35 
36 double Kruskal() {
37     int cnt = 0;
38     double ans = 0;
39     sort(edge + 1, edge + m + 1, cmp);
40     for(int i = 1; i <= n; i ++) {
41         G[i].clear();
42         G[i].push_back(i);
43         head[i] = i;
44     }
45     for(int i = 1; i <= m; i ++) {
46         int fx = Find(edge[i].u), fy = Find(edge[i].v);
47         if(cnt == n - 1) break;
48         if(fx != fy) {
49             edge[i].vis = true;
50             ans += edge[i].w;
51             cnt ++;
52             int len_fx = G[fx].size(), len_fy = G[fy].size();
53             for(int j = 0; j < len_fx; j ++) {
54                 for(int k = 0; k < len_fy; k ++) {
55                     Max[G[fx][j]][G[fy][k]] = Max[G[fy][k]][G[fx][j]] = edge[i].w;
56                 }
57             }
58             head[fx] = fy;
59             for(int j = 0; j < len_fx; j ++) {
60                 G[fy].push_back(G[fx][j]);
61             }
62         }
63     }
64     if(cnt < n - 1) return INF;
65     return ans;
66 }
67 
68 double Second_Kruskal(double MST) {
69     double ans = 0;
70     for(int i = 1; i <= m; i ++) {
71         ans = max(ans, edge[i].population / (MST - Max[edge[i].u][edge[i].v]));
72     }
73     return ans;
74 }
75 
76 int main () {
77     int t;
78     scanf("%d", &t);
79     while(t --) {
80         m = 0;
81         scanf("%d", &n);
82         for(int i = 1; i <= n; i ++) {
83             scanf("%d %d %d", &city[i].u, &city[i].v, &city[i].population);
84         }
85         for(int i = 1; i <= n - 1; i ++) {
86             for(int j = i + 1; j <= n; j ++) {
87                 edge[++m].u = i;
88                 edge[m].v = j;
89                 edge[m].vis = false;
90                 edge[m].population = city[i].population + city[j].population;
91                 edge[m].w = Distance(i, j);
92             }
93         }
94         double MST = Kruskal();
95         double ans = Second_Kruskal(MST);
96         printf("%.2f\n", ans);
97     }
98     return 0;
99 }