#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <math.h>
#include <string.h>
#include <time.h>
#include <sys/stat.h>
#include <errno.h>
#include <mpi.h>


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

	int id, p, n, ln, i, j, retCode;
	double *buffer;
	
	MPI_Init(&argc, &argv);
    MPI_Comm_size(MPI_COMM_WORLD, &p);
    MPI_Comm_rank(MPI_COMM_WORLD, &id);
    
    n = strtol(argv[1],NULL,10); // total number of elements to be distributed
    
    ln = n/p;	// local number of elements
    
    buffer = (double*)calloc(ln, sizeof(double));
    
	if (id == p-1)	// Process p-1 send to other processes
  	{
		for (i=0; i< p-1; i++)
		{
			fprintf(stdout, "Process %d is sending %d elements to process %d\n", p-1, ln, i);
			retCode = MPI_Ssend (buffer, ln, MPI_DOUBLE, i, 0, MPI_COMM_WORLD);

			if(retCode)
				fprintf(stdout, "MPISend error at file %s, line %d  code %d\n", __FILE__, __LINE__, retCode);
			
			fprintf(stdout, "Process %d completed sending to process %d\n", p-1, i);
			
		}

	} 
	else	// other processes receive from process p-1
	{
		fprintf(stdout, "Process %d is receiving %d elements from process %d\n", id, ln,p-1);
		retCode = MPI_Recv (buffer, ln, MPI_DOUBLE, p-1, MPI_ANY_TAG, MPI_COMM_WORLD, MPI_STATUS_IGNORE);
		if(retCode)
			fprintf(stdout, "MPI_Recv error at file %s, line %d  code %d\n", __FILE__, __LINE__, retCode);
		fprintf(stdout, "Process %d received from process %d\n", id, p-1);
	}
    
	free(buffer);

	
	MPI_Finalize();

	return 0;
}