Implement the "halo exchange" operation in the exchange() routine
in cpp/core.cpp or fortran/core.F90 with MPI_Sendrecv.
Note that at least the steps 1 and 2 in the base exercise need to be completed for this exercise.
Implement the "halo exchange" operation in the exchange() routine
in cpp/core.cpp or fortran/core.F90 with MPI_Sendrecv.
Note that at least the steps 1 and 2 in the base exercise need to be completed for this exercise.