/* From: "COMPUTATIONAL PHYSICS, 2nd Ed" 
   by RH Landau, MJ Paez, and CC Bordeianu 
   Copyright Wiley-VCH 2007.
   Electronic Materials copyright: R Landau, Oregon State Univ, 2007;
   MJ Paez, Univ Antioquia, 2007; & CC Bordeianu, Univ Bucharest, 2007
   Support by National Science Foundation                              
*/  
// deadlock-fixed.c: deadlock.c without deadlock by Phil. Carter

#include <stdio.h>
#include "mpi.h"
#define MAXLEN 100

main(int argc, char *argv[])  {
	
  int myrank, numprocs, torank, i;
  char tosend[MAXLEN], received[MAXLEN];
  MPI_Status status;
  MPI_Init(&argc,&argv);
  MPI_Comm_rank(MPI_COMM_WORLD,&myrank);
  MPI_Comm_size(MPI_COMM_WORLD,&numprocs);
  if (myrank == numprocs - 1) torank = 0;
  else torank = myrank + 1;
  // Save the string to send in the variable tosend:
  sprintf(tosend,"Message from node %d to %d\n", myrank, torank);
  for (i = 0; i < numprocs; i++)  {
    if (myrank == i)
            MPI_Send(tosend,MAXLEN,MPI_CHAR,torank,i,MPI_COMM_WORLD);
    else if (myrank == i+1 || (i == numprocs - 1 && myrank == 0))
       MPI_Recv(received,MAXLEN,MPI_CHAR,i,i,MPI_COMM_WORLD,&status);
    }
    printf("%s",received);        // Print after successful receive
    MPI_Finalize();
    exit(0);
}