CF1210A Anadi and Domino

 1 #include <bits/stdc++.h>
 2 using namespace std;
 3 int check(vector<int>& v, set<pair<int, int>>& st)
 4 {
 5     int res = 0;
 6     map<pair<int, int>, int> mp;
 7     for (int i = 1; i <= 6; i++)
 8     {
 9         for (int j = i; j <= 6; j++)
10         {
11             mp[make_pair(i, j)] = 0;
12         }
13     }
14     for (auto it: st)
15     {
16         int a = v[it.first - 1], b = v[it.second - 1];
17         pair<int, int> tmp(min(a, b), max(a, b));
18         if (mp[tmp] == 0)
19         {
20             mp[tmp] = 1; res++;
21         }
22     }
23     return res;
24 }
25 int main()
26 {
27     int n, m, a, b;
28     while (cin >> n >> m)
29     {
30         set<pair<int, int>> st;
31         for (int i = 0; i < m; i++)
32         {
33             cin >> a >> b;
34             st.insert(make_pair(min(a, b), max(a, b)));
35         }
36         if (n <= 6) { cout << m << endl; continue; }
37         vector<int> a{1, 1, 2, 3, 4, 5, 6};
38         int maxn = 0;
39         do
40         {
41             maxn = max(maxn, check(a, st));
42         } while (next_permutation(a.begin(), a.end()));
43         cout << maxn << endl;
44     }
45     return 0;
46 }