BestCoder Round #41 1002

 1 /*140MS*/
 2 #include<iostream>
 3 #include<string>
 4 #include<map>
 5 #include<algorithm>
 6 #include<cstring>
 7 #define rep(i, n) for(int i = 0 ; i < n ; i++)
 8 using namespace std;
 9 string s; map<string, int> vis;
10 int gcd(int a, int b) {
11     if(a < b) swap(a, b);
12     return (b == 0)?a:gcd(b, a % b);
13 }
14 int main()
15 {ios::sync_with_stdio(false);
16     int T; cin >> T;
17     while(T--) {
18         int n; cin >> n;
19         int ans = 0;
20         int toteven = 0; int totodd = 0; vis.clear();
21         rep(i ,n) {
22             cin >> s;
23             if(s.length() % 2 == 1) {
24                 ans += toteven; if(vis.count(s)) ans += vis[s];
25                 if(!vis.count(s)) vis[s] = 0; vis[s]++;
26                 totodd++;
27             }
28             else {
29                 ans += totodd; if(vis.count(s)) ans += vis[s];
30                 if(!vis.count(s)) vis[s] = 0; vis[s]++;
31                 toteven++;
32             }
33         }
34         if(ans == 0) cout << "0/1" << endl;
35         else {
36             int b = (n * (n - 1)) / 2;
37             int t = gcd(ans, b);
38             cout << ans / t << "/" << b / t << endl;
39         }
40     }
41     return 0;
42 }