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");

         }

     }

  }