hdu1258 dfs 给一个指定的target数和一个数列，要求不重复选择其中的数使得和为target并打印，结果不可重复。

 #include<bits/stdc++.h>
 using namespace std;
 typedef unsigned int ui;
 typedef long long ll;
 typedef unsigned long long ull;
 #define pf printf
 #define prime1 1e9+7
 #define prime2 1e9+9
 #define scand(x) scanf("%llf",&x)
 #define f(i,a,b) for(int i=a;i<=b;i++)
 #define scan(a) scanf("%d",&a)
 #define dbg(args) cout<<#args<<":"<<args<<endl;
 #define pb(i) push_back(i)
 #define ppb(x) pop_back(x)
 #define maxn 100
 int n,m,t,cnt;
 int a[maxn],b[maxn];
 void dfs(int sum,int posa,int posb)
 {
     if(sum>m)return;
     if(sum==m)
     {
         cnt++;
         f(i,,posb-)
         {
             if(i!=)
             {
                 pf("+%d",b[i]);
             }
             else pf("%d",b[]);
         }
         pf("\n");
         return;
     }
     f(i,posa,n)
     {
         b[posb]=a[i];
         dfs(sum+b[posb],i+,posb+);
         while(i+<=n&&a[i]==a[i+])i++;
     }
     return ;
 }
 int main()
 {
     std::ios::sync_with_stdio(false);
     //freopen("input.txt","r",stdin);
     //freopen("output.txt","w",stdout);
     while(scanf("%d %d",&m,&n)==&&!(n==&&m==))
     {
         cnt=;
         memset(a,,sizeof(a));
         memset(b,,sizeof(b));
         f(i,,n)scan(a[i]);
         sort(a+,a+n+,greater<int>());
         pf("Sums of %d:\n",m);
         dfs(,,);
         if(!cnt)
         {
             pf("NONE\n");
         }
     }
  }