#include <stdio.h>
#include <unistd.h>
#include <mpi.h>
#include <stdlib.h>
#include <math.h>

//Example compilation
//mpicc random_comm_starter.c -lm -o random_comm_starter

//Example execution
//mpirun -np 1 -hostfile myhostfile.txt ./random_comm_starter

//Do not change the seed, or your answer will not be correct
#define SEED 72

//Change this if you want, but make sure it is set to 10 when submitting the assignment
#define TOTALITER 10

//Size corresponds to 10 MiB of integers
#define NCOUNTER 2621437 

int generateRandomRank(int max_rank, int my_rank);

int main(int argc, char **argv) {
  int i, my_rank, nprocs;

  MPI_Init(&argc,&argv);
  MPI_Comm_rank(MPI_COMM_WORLD,&my_rank);
  MPI_Comm_size(MPI_COMM_WORLD,&nprocs);

  //alloc the counter to be a 10 MiB buffer
  int * counter = (int *)calloc(NCOUNTER, sizeof(int));

  if (nprocs<3)
  {
    if (my_rank==0)
    printf("\nRun with at least 3 ranks.\n\n");
    MPI_Finalize();
    return 0;
  }

  //seed rng do not modify
  srand(SEED+my_rank);


  //WRITE CODE HERE  

  

  MPI_Finalize();
  return 0;
}


//Do not modify the rank generator or you will get the wrong answer
//returns a rank between 1 and max_rank, but does not return itself
//does not generate rank 0
int generateRandomRank(int max_rank, int my_rank)
{
  
  int tmp=round(max_rank*((double)(rand()) / RAND_MAX));
  while(tmp==my_rank || tmp==0)
  {  
  tmp=round(max_rank*((double)(rand()) / RAND_MAX)); 
  }

  return tmp;
}