std::vector<bool> async

#include <iostream>
#include <future>
#include <vector>

constexpr int N = (int) 1e7;
constexpr int threads = 10;

std::vector<bool> all(N);

int main() {
    std::vector<std::future<void>> futures;
    for (int it = 0; it < threads; it++) {
        auto f = std::async(std::launch::async, [it]{
            for (int i =0 ; i < N; i++) {
                if (i % threads == it) {
                    all[i] = true;
                }
            }
        });
        futures.push_back(std::move(f));
    }
    for (auto &f : futures) {
        f.get();
    }
    int sum = 0;
    for (bool z : all) {
        sum += (z ? 1 : 0);
    }
    std::cerr << sum << std::endl;
}