Obtaining list of keys and values from unordered_map

Question

What is the most efficient way of obtaining lists (as a vector) of the keys and values from an unordered_map?

For concreteness, suppose the

Answer 1

Joining late, but thought this might be helpful to someone.
Two template functions making use of key_type and mapped_type.

namespace mapExt
{
    template
    std::vector Keys(const myMap& m)
    {
        std::vector r;
        r.reserve(m.size());
        for (const auto&kvp : m)
        {
            r.push_back(kvp.first);
        }
        return r;
    }

    template
    std::vector Values(const myMap& m)
    {
        std::vector r;
        r.reserve(m.size());
        for (const auto&kvp : m)
        {
            r.push_back(kvp.second);
        }
        return r;
    }
}

Usage:

std::map mO;
std::unordered_map mU;
// set up the maps
std::vector kO = mapExt::Keys(mO);
std::vector kU = mapExt::Keys(mU);
std::vector vO = mapExt::Values(mO);
std::vector vU = mapExt::Values(mU);