1 #include <iostream> 2 #include <cstdio> 3 #include<algorithm> 4 #include <cstring> 5 using namespace std; 6 int ap[30],visit[30]; 7 int l,n; 8 int dfs(int len,int gen,int iqq) 9 {10     if (gen==3)11         return 1;12     for(int i=iqq; i<n; i++)13     {14         //cout<<visit[len]<<endl;15         if (!visit[i])16         {17             visit[i]=1;18             if (len+ap[i]==l)19             {20                 //cout<<len<<endl;21                 if(dfs(0,gen+1,0))22                     return 1;23             }24             else if (len+ap[i]<l)25             {26                 //cout<<len<<endl;27                 if(dfs(len+ap[i],gen,i)) return 1;28             }29             visit[i]=0;30         }31     }32     return 0;33 }34 int main ()35 {36     int t,sum;37     while (cin>>t)38     {39         while (t--)40         {41             cin>>n;42             sum=0;43             //Max=0;44             for (int i=0; i<n; i++)45             {46                 cin>>ap[i];47                 sum+=ap[i];48             }49             memset(visit,0,sizeof(visit));50             sort(ap,ap+n);51             if (sum%4==0&&n>=4&&ap[n-1]<=sum/4)52             {53 54                 l=sum/4;55                 if (dfs(0,0,0))56                     printf ("yes\n");57                 else58                     printf ("no\n");59                 //cout<<n<<endl;60             }61             else printf ("no\n");62         }63     }64 }