#include <vector>
#include <thread>
#include <iostream>
#include <random>
#include <chrono>
#include <utility>
#include <future>
#include <algorithm>
using tt = std::pair<std::future<int>, std::thread>;
std::mutex mtx;
std::condition_variable cv;
bool ready = false;

void func(std::promise<int> && p) {
    std::unique_lock<std::mutex> lck(mtx);
  while (!ready) cv.wait(lck);
    auto start = std::chrono::high_resolution_clock::now();
    for (int j = 1000000 ; j ; --j) {
        for(int i = 0 ; i < 10; i++) {
            int x = i * j;
        }
    }
    auto stop = std::chrono::high_resolution_clock::now();
    p.set_value( std::chrono::duration_cast<std::chrono::milliseconds>(stop - start).count());
}
void go() {
  std::unique_lock<std::mutex> lck(mtx);
  ready = true;
  cv.notify_all();
}
int mean(const std::vector<int>& v) {
    if (v.size() ==0 ) return 0;
    return std::accumulate( v.begin(), v.end(), 0.0) / v.size();
}
double percentbelow(const std::vector<int>& v, int th) {
   double i = 0;
   for (const auto& it : v) {
       if(it < th) {
           i++;
       } else {
          break;
       }
   }
   return i/v.size();
}
int main(int argc, char** argv)
{
    int thcount = std::stoi(argv[1]);
    std::vector<tt> results;
    for(int i = 0 ; i < thcount ; i++) {
        std::promise<int> p;
        auto f = p.get_future();
        results.push_back(tt(std::move(f), std::thread(func, std::move(p))));
    }
    std::vector<int> times;
    auto start = std::chrono::high_resolution_clock::now();
    go();
    for(auto& i : results) {
        if(i.second.joinable()) i.second.join();
        times.push_back(i.first.get());
    }
    auto stop = std::chrono::high_resolution_clock::now();
    std::sort (times.begin(), times.end());
    int av = mean(times);
    int min = times[0];
    int max = times[times.size()-1];
    std::cout << "###################\nFor " << times.size() << " threads got: \n";
    std::cout << "\n# whole: " << std::chrono::duration_cast<std::chrono::milliseconds>(stop - start).count() << "[ms]";
    std::cout << "\n# mean: " << av << "[ms]";
    std::cout << "\n# min: " << min << "[ms]";
    std::cout << "\n# max: " << max << "[ms]";
    std::cout << "\n# below mean: " << percentbelow(times, av) * 100 << " %";
    std::cout << "\n# below 25 [ms]: " << percentbelow(times, 25)*100 << " % \n";
    return 0;
}