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

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

  int world_rank, row_rank, col_rank, cart_rank;
  int nprocs, row_size, col_size;
  int coords[2], sub_coords[2];
  int dims[2] = { 0, 0}, period[2] = { 1, 1};
  int src_rank, dst_rank;
  int sum, temp;
  float avg;

  MPI_Comm cart_grid, cart_row, cart_col;
  MPI_Status status;

  /* MPI Initialization */
  MPI_Init(&argc, &argv);
  MPI_Comm_size(MPI_COMM_WORLD, &nprocs);
  MPI_Comm_rank(MPI_COMM_WORLD, &world_rank);

  /* Cartesian grid creation:
   * - the function MPI_Dims_create may be used to compute dimensions in both directions
   * - MPI_Cart_create must be used to create the new topology
   * - cart_grid will be the handle of the new topology
   */
	---
  /* Local world_rank initialization and comparison to global world_rank:
   * - how can you get cart_rank?
  */
	---

  printf ("I am world_rank %d in MPI_COMM_WORLD and world_rank %d in the cartesian communicator\n",
      world_rank, cart_rank);

  /* Coordinates creation and neighbour communication 
   *  - get process cartesian coordinates 'coords' with function MPI_Cart_coords
  */
	---

  /* Communication south:
   * - use MPI_Cart_shift and MPI_Sendrecv properly to send local rank to the neighbours
   * - receive neighbour rank in 'temp' variable and store sum in 'sum'
  */
	---
	
  /* Communication north */
	---

  /*Communication east */
	---

  /*Communication west */
	---

  /*Neighbour's average */
  avg = (float) sum / 5;
  printf("Cart rank %d (%d, %d), neighbours average: %.2f\n", cart_rank, coords[0], coords[1], avg);

  /*Row sub-communicator creation:
   * - how would you create a "row sub-communicator" ?
   * - use the function MPI_Cart_sub to get 'cart_row' communicator handle 
   * - use the proper functions to get 'row_size' and 'row_rank'
  */
  sum = 0;
  sub_coords[0] = 0;
  sub_coords[1] = 1;
	---
	
  /* Use MPI_Reduce to sum up ranks in row sub-communicator */
	---

  if (row_rank == 0) {
    avg = (float) sum / row_size;
    printf("Row %d, row average: %.2f\n", coords[0], avg);
  }

  /*Column sub-communicator creation:
   * - repeate to obtain 'cart-col' comm-handle and 'col_size' and 'col_rank' 
  */
  sum = 0;
  sub_coords[0] = 1;
  sub_coords[1] = 0;
	---

  /* Use MPI_Reduce to sum up ranks in row sub-communicator */
	---

  if (col_rank == 0) {
    avg = (float) sum / col_size;
    printf("Column %d, column average: %.2f\n", coords[1], avg);
  }

  /* Finalization operations */
  MPI_Comm_free(&cart_grid);
  MPI_Comm_free(&cart_col);
  MPI_Comm_free(&cart_row);
  MPI_Finalize();

  return 0;
}