#include "mpi.h"
int main(int argc, char **argv)
{
 int rank,size,tag=0,i; 
 int recvd_from;
 MPI_Status status;
 MPI_Request	send_request,recv_request;
 char msg[20];
 double t1,t2;

 MPI_Init(&argc, &argv);
 MPI_Comm_rank(MPI_COMM_WORLD, &rank);
 MPI_Comm_size(MPI_COMM_WORLD, &size);
 if(rank == 0) 
   {
    t1 = MPI_Wtime();
    strcpy(msg,"Hello World!\n");
    for(i=1;i<size;i++)
      MPI_Isend(msg,20,MPI_CHAR,i,tag,MPI_COMM_WORLD,&send_request);

    for(i=1;i<size;i++)
      {
       MPI_Irecv(msg,20,MPI_CHAR,i,tag,MPI_COMM_WORLD,&recv_request);
       MPI_Wait(&recv_request, &status);
       printf("Recebi %s \n", msg);
      }
    t2 = MPI_Wtime();
    printf ("Tempo total = %.6f\n", t2 -t1);   
   }
 else 
   {
    MPI_Irecv(msg,20,MPI_CHAR,0,tag,MPI_COMM_WORLD,&recv_request);
    for (i=0; i< 100000; i++);
    MPI_Wait(&recv_request, &status);
    printf("Message received: %s\n",msg);
    strcpy(msg, "Escravo");
    MPI_Isend(msg,20,MPI_CHAR,0,tag,MPI_COMM_WORLD,&send_request);
   }
 MPI_Finalize();
 return 0;
}