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

using namespace std;


int main () {
   vector <pid_t> procs;
   vector <pid_t>::iterator pos;

   int i;

   pid_t parentPID;
   pid_t pid;
   int status;

   parentPID =  getpid();
   int options = 0;

   // serve up a heaping helping of processes.
   for(i=0;i<10;i++) {
      if (parentPID == getpid()) {
          pid = fork();
	  if (pid != 0) {
	      procs.push_back(pid);
	  }
      }
   }

   if (pid == 0) {
      int sleepTime;

      cout << "\tChild here " << endl;
      srand(getpid());
      sleepTime = rand() % 20 + 5 ;
      cout << "\tChild " << getpid() << " sleeping for " << sleepTime << endl;
      sleep (sleepTime);
      cout << "\tChild " << getpid() << " exiting " << endl;
      return 0;

   } else {

      cout << "Parent here with " << procs.size() << " children " << endl;
      while (procs.size() > 0) {
          pid_t child;
          pid = procs[procs.size()-1];

	  //options = WNOHANG;

          cout << "Parent waiting on " << pid << endl;
          child = waitpid(pid,&status, options);
	  if (child != 0) {
	      cout << "Parent, child " << child << " just exited " << endl;
	      pos = find(procs.begin(), procs.end(),child);
	      if (pos != procs.end()) {
	          procs.erase(pos);
	      }
	  }
	  cout << "Parent still has " << procs.size() << " children " << endl;

      }
   }

   return 0;

}