#include <iostream>
#include <unistd.h>
#include <sys/wait.h>
#include <vector>
#include <cstdlib>
#include <ctime>
#include <cmath>

void random_task(int id) {
	srand(time(0));
	int delay=1+rand()%3;
	std::cout<<"PID: "<<getpid()<<", PPID: "<<getppid()<<", task: "<<id<<" delay: "<<delay<<"s\n";
	sleep(delay);
}

int main() {
	int total=6;//tasks
	int levels=2;//workers
	pid_t root=getpid();
	// Collective fork: children continue the loop
	for(int i=0;i<levels;++i) {
		pid_t pid=fork();
	}
	// Workers:all processes except root
	if(getpid()!=root) {
		int worker_id=getpid()%root;
		int worker_count=pow(2,levels)-1;
		for(int i=0;i<total;++i) {
			if(i%worker_count==worker_id%worker_count) {
				std::cout<<"["<<getpid()<<", "<<getppid()<<", id= "<<worker_id;
				random_task(i);
			}
		}
		_exit(0);
	}

	// Root reaps all descendants
	int status;
	while(1) {
		pid_t finished=waitpid(-1, &status, 0);
		if(finished>0) {
			std::cout<<"Reaped PID: "<<finished<<"\n";
			continue;
		}
		if(finished==-1 && errno==ECHILD) {
			break;
		}
	}
	return 0;
}