common numbers

[ChiaraItaly]

Hi! I have to create this code that is supposed to find the non common elements in two given vectors (of different lengths). Does anybody have an idea on how to do it? I was thinking about boolean variables but I'm not ssure about it :(
Thanks!

[MiiNiPaa]

#include <algorithm>
#include <iterator>

//...

//If you are not allowed to change original vectors:
std::vector<int> non_common(std::vector<int> lhs, std::vector<int> rhs)
{
    std::sort(lhs.begin(), lhs.end());
    std::sort(rhs.begin(), rhs.end());
    std::vector<int> result;

    //http://en.cppreference.com/w/cpp/algorithm/set_symmetric_difference
    std::set_symmetric_difference(lhs.begin(), lhs.end(), 
                                  rhs.begin(), rhs.end(),
                                  std::back_inserter(result)); //http://en.cppreference.com/w/cpp/iterator/back_inserter
    return result;
}