dfs

#include 
      
        #include 
       
         #include 
        
          #include 
         
           using namespace std; #define maxn 65 bool g[maxn][maxn]; int ans; int n; int c[maxn]; bool vis[maxn]; int lonely[maxn]; void check(int t) {
         memset(vis, 0, sizeof(vis));     memset(lonely, 0, sizeof(lonely)); for (int i = 0; i < t; i++)         vis[c[i]] = true; int temp = 0; for (int i = 1; i <= n - 1; i++) for (int j = i + 1; j <= n; j++) if (vis[i] == vis[j] && !g[i][j])             {
                     lonely[i]++;                 lonely[j]++;             } for (int i = 0; i < n; i++)         temp = max(temp, lonely[i]);     ans = min(ans, temp); } void dfs(int now, int t) {
     if (now > n) return; if (t >= n / 2)     {
             check(t); return;     }     c[t] = now;     dfs(now + 1, t + 1);     dfs(now + 1, t); } int main() {
     //freopen("t.txt", "r", stdin);     int a, b, maxa = 0;     ans = 0x3f3f3f3f; while (scanf("%d", &a) != EOF)     {
             maxa = max(a, maxa);         scanf("%d", &n); for (int i = 0; i < n; i++)         {
                 scanf("%d", &b);             g[a][b] = g[b][a] = true;         }     }     n = maxa;     dfs(1, 0);     printf("%d\n", ans); return 0; }