程序代码：

#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;
int main(int argc,char *argv[])
{
    int n;
    vector<int> vec;
    while(cin>>n){
    if( -1 == n)
        break;
    else
    {
        if( 0 == n )
        {
        sort(vec.begin(),vec.end());
        int count=0;
        for(vector<int>::iterator ix=vec.begin();ix!=vec.end();ix++)
        {
            for(vector<int>::iterator jx=ix;jx!=vec.end();jx++)
            {
            int m=2*(*ix);
            if( m == *jx )
                count++;
            }
        }
        cout<<count<<endl;
        vec.erase(vec.begin(),vec.end());
        }
        else
        vec.push_back(n);
    }
    }
    return 0;
}

程序代码：

#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;
int main(int argc,char *argv[])
{
    int s,k=0;
    vector<int> vec;
    cin>>s;
    while(k<s){
    cout<<"Scenario #"<<++k<<endl;
    int m,n,tmp,sum=0;
    cin>>m>>n;
    for( int i=0; i < n;i++)
    {
        cin>>tmp;
        vec.push_back(tmp);
    }
    sort(vec.begin(),vec.end());
    int count=0;
    while(sum<m && !vec.empty())
    {
        sum+=vec.back();
        vec.pop_back();
        count++;
    }
    if(vec.empty()&&sum<m )
    {
        cout<<"impossible"<<endl;
    }
    else
    {
        cout<<count<<endl;
    }
    }
    return 0;
}