q3.cpp

#include <set>
#include <vector>
#include <iterator>
#include <iostream>
using namespace std;

struct even_compare
{
    bool operator()(const int &lhs, const int &rhs) const
    {
        if (lhs & 1 && rhs & 1)
        {
            return lhs < rhs;
        }
        else if (lhs & 1)
        {
            return false;
        }
        else if (rhs & 1)
        {
            return true;
        }

        // both are even
        return lhs < rhs;
    }
};

int main()
{
    set<int> x{3, 2, 6, 8, 1, 9, 5, 7};
    copy(x.begin(), x.end(), ostream_iterator<int>(cout, ", "));
    cout << '\n';

    vector<int> v{3, 3, 4, 1, 1, 4, 2, 3, 2};

    x.insert(v.begin(), v.end());
    copy(x.begin(), x.end(), ostream_iterator<int>(cout, ", "));
    cout << '\n';

    set<int, even_compare> w;

    // copy contents from x to w
    copy(x.begin(), x.end(), inserter(w, w.begin()));

    copy(w.begin(), w.end(), ostream_iterator<int>(cout, ", "));
    cout << '\n';
}