/* -*- Mode: C; c-basic-offset:4 ; indent-tabs-mode:nil ; -*- */

/*

 *  (C) 2003 by Argonne National Laboratory.

 *      See COPYRIGHT in top-level directory.

 */

#include <stdio.h>

#include <stdlib.h>

#include <mpi.h>

#include "mpitestconf.h"

#define LOOPS 100

int main(int argc, char **argv)

{

    int rank, size, i, j, count;

    MPI_Group full_group, sub_group;

    int *included, *ranks;

    MPI_Comm comm;

    MPI_Init(NULL, NULL);

    MPI_Comm_rank(MPI_COMM_WORLD, &rank;;

    MPI_Comm_size(MPI_COMM_WORLD, &size);

    ranks = malloc(size * sizeof(int));

    included = malloc(size * sizeof(int));

    MPI_Comm_group(MPI_COMM_WORLD, &full_group);

    for (j = 0; j < LOOPS; j++) {

        srand(j);       /* Deterministic seed */

        count = 0;

        for (i = 0; i < size; i++) {

            if (rand() % 2) {   /* randomly include a rank */

                included[i] = 1;

                ranks[count++] = i;

            }

            else

                included[i] = 0;

        }

        MPI_Group_incl(full_group, count, ranks, &sub_group);

        if (included[rank]) {

            MPI_Comm_create_group(MPI_COMM_WORLD, sub_group, 0, &comm);

            MPI_Barrier(comm);

            MPI_Comm_free(&comm);

        }

        MPI_Group_free(&sub_group);

    }

    MPI_Group_free(&full_group);

    if (rank == 0)

        printf(" No Errors\n");

    free(ranks);

    free(included);

    MPI_Finalize();

    return 0;

}