[c++] iter by index

// position is the std::vector<int> of index position
// src.erase(byIndices(src, begin(position), end(position)), src.end());
// position.clear();

template<typename Cont, typename It>
auto iterByIndices(Cont &cont, It beg, It end) -> decltype(std::end(cont))
{
    int helpIndx(0);
    return std::stable_partition(std::begin(cont), std::end(cont),
        [&](decltype(*std::begin(cont)) const& val) -> bool {
        return std::find(beg, end, helpIndx++) == end;
    });
}