#include <iostream>
#include <sstream>
#include <string>
#include <cstdlib>
#include <omp.h>
using namespace std;

#define ARRLEN 1048576

long count = 0;

string formatval(int ct, int id, int val) {
  ostringstream s;
  s << "[" << ct << "(" << id << "): multiply by " << val << "]" << endl;
  return s.str();
}

void func(long long arr[], int val, int threadid) {
  count++;
  int j;

  cout << formatval(count, threadid, val);

  for (j = 0;  j < ARRLEN;  j++)
    arr[j] *= val;

  cout << formatval(count, threadid, val);
}

int main(int argc, char ** argv)
{
  long long arr[ARRLEN];
  int i; // loop control
  const int prod = 2*3*5*7*11*13;  
  ostringstream s;
  int threadct = 8;  /* number of threads available*/
   
  /* parse command-line arg for number of threads */
  if (argc > 1)
    threadct = atoi(argv[1]);

  omp_set_num_threads(threadct);

#pragma omp parallel default(shared)
  {

#pragma omp for  private(i) 
    for (i = 0;  i < ARRLEN;  i++)
      arr[i] = prod*i+1;
    
    // assert:  no element of arr[i] is divisible by a factor of prod
    
#pragma omp sections
    {
#pragma omp section
      func(arr, 2, omp_get_thread_num());
      
#pragma omp section
      func(arr, 3, omp_get_thread_num());
      
#pragma omp section
      func(arr, 5, omp_get_thread_num());
      
#pragma omp section
      func(arr, 7, omp_get_thread_num());
      
#pragma omp section
      func(arr, 11, omp_get_thread_num());
      
#pragma omp section
      func(arr, 13, omp_get_thread_num());
      
    }

#pragma omp for  private(i, s) 
  for (i = 0;  i < ARRLEN;  i++)
    if (arr[i] % prod != 0) {
      s.str("");
      s << "arr[" << i << "] == " << arr[i] 
	<< " is not divisible by prod" << endl;
      cout << s.str();
    }
      

  }

  cout << "At end, count = " << count << endl;
  return 0;
}