From your example I am guessing you are asking how to construct the vector of unique_ptr's to Elf and populate. Like so:
vector<unique_ptr<Elf>> vec_uniqptrElf;
for (auto i = 0; i < 10000; ++i) {
vec_uniqptrElf.push_back(
unique_ptr<Elf>(new Elf(90)));
}