#include <iostream>
#include <optional>
#include <vector>
#include <algorithm>
#include <set>
#include <iterator>

int main() {

	auto optVec = std::make_optional<std::vector<int>>(3, 22); //{22, 22, 22}
	std::set<int> ints{4, 7, 1, 41,100};
	optVec.emplace(std::begin(ints), std::end(ints));
	std::copy(optVec->begin(), optVec->end(), std::ostream_iterator<int>(std::cout, ", "));
	
    return 0;
}

jieguo

1, 4, 7, 41, 100,