#include <stdio.h>
#include "mpi.h"

#define N 800

int main( argc, argv )
int  argc;
char **argv;
{
    int ierr;
    int rank, size;

    MPI_Init( &argc, &argv );
    MPI_Comm_size( MPI_COMM_WORLD, &size );
    MPI_Comm_rank( MPI_COMM_WORLD, &rank );



    int a[size*N];
    int b[size*N];
    int c[size*N];

    for (int i=0;i<size*N;i++)
    {
     b[i]=i;
     c[i]=i+4;
    }

    int ista,iend;





    ista = N * rank;
    iend = ista + N;

    int A=0,B=0,C=0;

    for (int i=ista;i<iend;i++)
    {
     a[i] = b[i] + c[i];
     A+=a[i];
     B+=b[i];
     C+=c[i];
    }

    printf("%d +%d = %d on processor #%d of processors #%d\n",B,C,A,rank,size);
    int V[size];

    int R;

    MPI_Status status;

    int received;

    if (rank == 0) {
      received = 1;
    }

    V[rank]=A;

    int T;

    if (rank == 0) {
      T=V[0];
      while (received<size) {
      ierr = MPI_Recv(&R,1,MPI_INT,
                      MPI_ANY_SOURCE,MPI_ANY_TAG,MPI_COMM_WORLD,
                      &status);
      V[status.MPI_SOURCE]=R;
      received++;
      T+=R;
      }
    } else {
      ierr = MPI_Send(&A,1,MPI_INT,0,1,MPI_COMM_WORLD);
      printf("I'm processor #%d and I have sent my subtotal of %d elements from element %d to element %d to processor #0\n",rank,N,ista,iend-1);
    }

    if (rank == 0 ) {
      printf("Master processor #0 has all results as following:\n");
      for (int i=0;i<size;i++) {
        printf("%d ",V[i]);
      }
      printf("\n");
      printf("While receiveing subtotals of %d elements, processor #0 has computed the total of %d (%d * %d processors) elements from element %d to element %d that is %d\n",N,N*size,N,size,0,N*size-1,T);
    }

    MPI_Finalize();
    return 0;
}