> #include<iostream>
> #include<algorithm>
> using namespace std;
> 
> const int size=21;
> int sq[size];
> bool visit[size];
> int start;
> int n;
> 
> bool cmp(int a,int b){
> 	return a>b;
> }
> 
> bool dfs(int m,int left,int len){
> 	if(m==0&&left==0)
> 		return true;
> 	int i;
> 	if(left==0){
> 		i=0;
> 		left=len;
> 	}
> 	else i=start+1;
> 	for(;i<n;i++){
> 		if(visit[i]||left<sq[i])
> 			continue;
> 		start=i;
> 		visit[i]=true;
> 		if(dfs(m-1,left-sq[i],len))
> 			return true;
> 		else
> 			visit[i]=false;
> 		if(left==sq[i]||left==len)
> 			break;
> 	}
> 	return false;
> }
> 
> int main()
> {
> 	int t;
> 	cin>>t;
> 	while(t--){
> 		cin>>n;
> 		int sum=0;
> 		for(int i=0;i<n;i++){
> 			cin>>sq[i];
> 			sum+=sq[i];
> 		}
> 		if(sum%4){
> 			cout<<"no"<<endl;
> 			continue;
> 		}
> 		sort(sq,sq+n,cmp);
> 		if(dfs(n,0,sum/4))
> 			cout<<"yes"<<endl;
> 		else 
> 			cout<<"no"<<endl;
> 		fill(visit,visit+n,0);
> 	}
> 	system("pause");
> }
> 		

• Re:1011改装版—0MS (3) hitfrank 2010-06-02 15:12:48