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

#define ASIZE	100

void main(int argc, char **argv)
{
	int me, nprocs, namelen;
	char processor_name[MPI_MAX_PROCESSOR_NAME];
	int val[ASIZE], sval[ASIZE], rval[ASIZE], i, j, flag;
	MPI_Status status;

	MPI_Init(&argc, &argv);
	MPI_Comm_size(MPI_COMM_WORLD, &nprocs);
	MPI_Comm_rank(MPI_COMM_WORLD, &me);
	MPI_Get_processor_name(processor_name, &namelen);

	printf("I'm process %d of %d\n", me, nprocs);

	/* Initialize: stuff some bogus values in an array */
	for (j = 0; j < ASIZE; j++)
		val[j] = sval[j] = j * me;

	for (i = 0; i < nprocs; i++) {
		/* Send values to neighboring process */
		MPI_Send(sval, ASIZE, MPI_INT, (me < (nprocs-1) ? (me+1) : 0),
			i, MPI_COMM_WORLD);
		/* Receive values from neighboring process */
		MPI_Recv(rval, ASIZE, MPI_INT, MPI_ANY_SOURCE, i,
			MPI_COMM_WORLD, &status);
		for (j = 0; j < ASIZE; j++)
			sval[j] = rval[j];
	}

	for (j = flag = 0; j < ASIZE; j++)
		if (rval[j] != val[j]) flag++;

	if (flag)
		printf("%d: %d values were different!\n", me, flag);
	else
		printf("%d: No values were changed.\n", me);

	MPI_Finalize();
}