hdu 1258 Sum It Up

#include<cstdio>
#include<cstring>
#include<algorithm>
using namespace std;
int a[15],sum,n;
bool vis[15];
int flag;
void out()
{
	int f=1;
	flag=1;
	for(int i=1;i<=n;i++)
	{
		if(!vis[i]) continue;
		if(f) {printf("%d",a[i]);f=0;}
		else printf("+%d",a[i]);
	}
	printf("\n");
}
bool dfs(int pos,int tot)
{
	if(tot==sum)
	{
		out();				
		return 1;
	}
	for(int i=pos;i<=n;i++)
	{
		if(tot+a[i]<=sum&&!vis[i])
		{
			vis[i]=1;
			dfs(i+1,tot+a[i]);
			vis[i]=0;
			while(i<n&&a[i]==a[i+1])		//a[i]这个数字已经搜索过，再出现的话直接跳过
				i++;
		}
	}
	return 0;
}
int main()
{
	while(scanf("%d%d",&sum,&n)&&(sum||n))
	{
		flag=0;
		for(int i=1;i<=n;i++)
		{
			scanf("%d",&a[i]);
			vis[i]=0;
		}
		printf("Sums of %d:\n",sum);
		memset(vis,0,sizeof(vis));
		dfs(1,0);		
		if(!flag) printf("NONE\n");
	}
		return 0;
}