poj 2436 Disease Management

#include<iostream> #include<cstring> #include<cstdio> #include<cmath> #include<string> #include<algorithm> #define MAXN 1111 using namespace std; int cow[MAXN],vis[MAXN],N,D,K,ans; void dfs(int idx,int cnt,int sum){     if(cnt == K){         int num = 0;        for(int i = 0;i < N;i ++)  if(cow[i] == (cow[i] & sum)) num++;         ans = max(ans,num);         return;     }     for(int i = idx;i < D;i ++){         if(!vis[i]){  vis[i] = 1;  dfs(i+1,cnt+1,sum|(1 << i));  vis[i] = 0;         }     } } int main(){     int tmp,kind;     while(~scanf("%d%d%d",&N,&D,&K)){         memset(cow,0,sizeof(cow));         memset(vis,0,sizeof(vis));         for(int i = 0;i < N;i ++){  scanf("%d",&tmp);  for(int j = 0;j < tmp;j ++){      scanf("%d",&kind);      cow[i] |= (1 << (kind-1));  }         }         ans = 0;         dfs(0,0,0);         printf("%dn",ans);     }     return 0;}