> 大牛帮忙剪剪啊！！！
> 
> #include <iostream>
> #include <algorithm>
> using namespace std;
> 
> const int N = 4;
> int sticks[20];
> bool used[20];
> int m, side;
> 
> bool cmp ( int a, int b )
> {
> 	return a <= b;
> }
> 
> bool search ( int count, int left, int pos )
> {
> 	bool flag = false;
> 
> 	if ( count == N )
> 		return true;
> 	if ( left == side )
> 		flag = true;
> 
> 	for ( int i = 0; i < m; i++ )
> 	{
> 		if ( !used[i] )
> 		{
> 			if ( left > sticks[i] )
> 			{
> 				used[i] = true;
> 
> 				if ( search ( count, left - sticks[i], pos + 1 ) )
> 					return true;
> 				used[i] = false;
> 
> 				if ( flag )
> 					return false;
> 			}
> 			else if ( left == sticks[i] )
> 			{
> 				used[i] = true;
> 
> 				if ( search ( count + 1, side, 0 ) )
> 					return true;
> 				used[i] = false;
> 
> 				return false;
> 			}
> 		}
> 	}
> 
> 	return false;
> }
> 
> bool isbigger ()
> {
> 	for ( int i = 0; i < m; i++ )
> 		if ( sticks[i] > side )
> 			return true;
> 	return false;
> }
> 
> int main()
> {
> 	int t;
>     freopen ( "1909.txt", "r", stdin );
> 	for ( cin >> t; t > 0; t-- )
> 	{
> 		cin >> m;
> 
> 		for ( int i = 0; i < m; i++ )
> 			cin >> sticks[i];
> 
> 		sort ( sticks, sticks + m, cmp );
> 
> 		int len = 0;
> 		for ( int j = 0; j < m; j++ )
> 			len += sticks[j];
> 	
> 		side = len / N;
> 		if ( len % 4 != 0 || isbigger () )
> 		{
> 			cout << "no\n";
> 			continue;
> 		}
> 
> 		memset ( used, false, sizeof ( used ) );
> 
> 		if ( search ( 0, side, 0 ) )
> 			cout << "yes\n";
> 		else
> 			cout << "no\n";
> 	}
> 
> 	return 0;
> }