7_1

#include <iostream>
#include <mpi.h>
#include <stdio.h>
#include <math.h>

using namespace std;



int main(int argc, char** argv) {

    int newGroupOfProcesses[5] = { 8, 3, 9, 1, 6 };

    int rank;
    int world_size;
    MPI_Init(&argc, &argv);
    MPI_Comm_rank(MPI_COMM_WORLD, &rank);

    MPI_Comm_size(MPI_COMM_WORLD, &world_size);

    MPI_Status status;

    MPI_Group groupFirst;
    MPI_Group groupSecond;
    MPI_Comm_group(MPI_COMM_WORLD, &groupFirst);
    MPI_Group_incl(groupFirst, 5, newGroupOfProcesses, &groupSecond);

    MPI_Comm comm;
    MPI_Comm_create(MPI_COMM_WORLD, groupSecond, &comm);

    int current_rank = -1;

    int a[10];

    if (comm != MPI_COMM_NULL) {
        MPI_Comm_rank(comm, &current_rank);
    }

    if (current_rank == 0 && comm != MPI_COMM_NULL) {

        for (int i = 0; i < 10; i++) {

            a[i] = rand() % 10;

        }

        MPI_Bcast(&a, 10, MPI_INT, 0, comm);

    }

    if (current_rank != -1 && comm != MPI_COMM_NULL) {

        MPI_Bcast(&a, 10, MPI_INT, 0, comm);

        cout << "Process number " << current_rank << " with array: " << endl;

        for (int i = 0; i < 10; i++) {

            cout << a[i] << " ";

        }

        cout << endl;

        if (current_rank == 4) {

            MPI_Send(a, 10, MPI_INT, 0, 0, MPI_COMM_WORLD);

        }

    }

    if (rank == 0) {

        MPI_Recv(a, 10, MPI_INT, 6, 0, MPI_COMM_WORLD, &status);

        cout << "Array of results " << endl;

        for (int i = 0; i < 10; i++) {

            cout << a[i] << " ";

        }

        cout << endl;

    }

    if (comm != MPI_COMM_NULL) {

        MPI_Comm_free(&comm);

    }

    MPI_Group_free(&groupSecond);
    MPI_Finalize();
    return 0;
}