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

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();
	std::vector<pid_t>pids;
	int worker_id;
	int worker_count=levels;
	// Root spawns children and stores PIDs
	for(int i=0; i<levels; ++i) {
		if(getpid()!=root) {
			break;
			//_exit(0);
		}
		pid_t pid=fork();
		if(pid==0) {
			std::cout<<"["<<getpid()<<", "<<i<<std::endl;
			worker_id=i;
			break;
		}
		else {
			pids.push_back(pid);
		}
	}

	// Root reaping loop
	if(getpid()==root) {
		int status;
		while(1) {
			pid_t finished=waitpid(-1, &status, 0);
			if(finished>0) {
				std::cout<<"Reaped PID: "<<finished<<"\n";
				pids.erase(std::remove(pids.begin(),pids.end(),finished),pids.end());
				continue;
			}
			if(finished==-1 && errno==ECHILD) {
				break;
			}
		break;
		}
	}
	else {
		// Work distribution(modulo)
		for(int i=0; i<total;++i) {
			if(i%worker_count==worker_id ){
				random_task(i);
			}
		}
	}
	return 0;
}