void my_bcast(void* data, int count, MPI_Datatype datatype, int root, MPI_Comm communicator) {
  int world_rank;
  MPI_Comm_rank(communicator, &world_rank);
  int world_size;
  MPI_Comm_size(communicator, &world_size);

  if (world_rank == root) {
    int i;
    for (i = 0; i < world_size; i++) {
      if (i != world_rank) {
        MPI_Send(data, count, datatype, i, 0, communicator);
      }
    }
  } else {
    MPI_Recv(data, count, datatype, root, 0, communicator,MPI_STATUS_IGNORE);
  }
}