123.cpp

#include <iostream>
#include <thread>
#include <chrono>

int myrand(int min, int max) 

{
  return rand()%(max-min)+min;
}

void lock(int& m) {
  m=1;
}

void unlock(int& m) {
  m=0;
}

void phil(int ph, int& ma, int& mb) {
  while(true) {
    int duration=myrand(1000, 2000);
    std::cout<<ph<<" thinks "<<duration<<"ms\n";
    std::this_thread::sleep_for(std::chrono::milliseconds(duration));

    lock(ma);
    std::cout<<"\t\t"<<ph<<" got ma\n";
    std::this_thread::sleep_for(std::chrono::milliseconds(1000));

    lock(mb);
    std::cout<<"\t\t"<<ph<<" got mb\n";

    duration=myrand(1000, 2000);
    std::cout<<"\t\t\t\t"<<ph<<" eats "<<duration<<"ms\n";
    std::this_thread::sleep_for(std::chrono::milliseconds(duration));

    unlock(mb);
    unlock(ma);
  }
}

int main() {
  std::cout<<"dp_1\n";
  srand(time(nullptr));

  int m1{0}, m2{0}, m3{0}, m4{0};

  std::thread t1([&] {phil(1, m1, m2);});
  std::thread t2([&] {phil(2, m2, m3);});
  std::thread t3([&] {phil(3, m3, m4);});
  std::thread t4([&] {phil(4, m4, m1);});

  t1.join();
  t2.join();
  t3.join();
  t4.join();
}