#ifndef SEMAPHORE_SEMAPHORE_H
#define SEMAPHORE_SEMAPHORE_H

class Semaphore {
 public:
  explicit Semaphore(int threads_cnt);
  void Wait();
  void Notify();
 private:
  int threads;
  std::mutex mut;
  std::condition_variable con_var;
};
Semaphore::Semaphore(int threads_cnt) {
  threads = threads_cnt;
}
void Semaphore::Wait() {
  std::unique_lock<std::mutex> lock(mut);
  if (threads == 0) {
    con_var.wait(lock);
    threads -= 1;
  }
}
void Semaphore::Notify() {
  std::unique_lock<std::mutex> lock(mut);
  if (threads < 0) {
    con_var.notify_one();
    threads++;
  }
}

#endif //SEMAPHORE_SEMAPHORE_H