code failing for multiple inputs

Here is a question of C++ that I was practising on some other site. The code is given below. My code fails for multiple inputs. the output is only clee olg
instead of clee olg sho col Given a string, S, of length N that is indexed from 0 to N-1, print its even-indexed and odd-indexed characters as space-separated strings on a single line. INPUT- The first line contains an integer, t (the number of test cases). Each line 'i' of the subsequent lines contain a String,S OUTPUT- For each String S(where 0<= j<=N-1), print S's even-indexed characters, followed by a space, followed by S's odd-indexed characters. . Eg- 2 college school output-

clee olg sho col

int main() 
{
    int t;
    cin>>t;
    string str;
    vector<string>s_even;
    vector<string>s_odd;
    for(int i=0;i<t;i++)
    {
        getline(cin,str);

        for(int j=0;j<str.size();j++)
        {        
            if(j%2==0)
                 { 
                   string  a;
                   a=str[j];
                   s_even.push_back(a);

                 }
             else
                 { 
                   string b;
                   b= str[j];
                   s_odd.push_back(b);
                  }
           }

copy(s_even.begin(),s_even.end(),ostream_iterator<string>(cout));

cout<<" ";

copy(s_odd.begin(),s_odd.end(),ostream_iterator<string>(cout));

 str.clear();
 s_odd.clear();
 s_even.clear();
 }
 return 0;

}