code example to min

to min

set<int>::iterator it1 = s1.begin();
    set<int>::iterator it2 = s2.begin();

    while(it1 != s1.end() && it2 != s2.end())
    {   
        if(*it1 < *it2)
        {   
            result.push_back(*it1);
            ++it1;
        }   
        else if(*it1 == *it2)
        {   
            ++it1;
            ++it2;
        }   
        else
        {   
            result.push_back(*it2);
            ++it2;
        }   
    }   
    if(it1 != s1.end())
        result.insert(result.end(),it1,s1.end());
    else if(it2 != s2.end())
        result.insert(result.end(),it2,s2.end());