#include <iostream>
#include <vector>
#include <memory>

struct Car {
};

using std::vector;
using std::shared_ptr;
using std::make_shared;

int main()
{
    int length = 3;
    auto cars = make_shared<vector<shared_ptr<Car>>>();
    for (int i = 0; i < length; i++) {
        cars->push_back(make_shared<Car>());
    }
}