parition_var_list Subroutine

  subroutine parition_var_list(list, marker)
    type(CFG_var_t), intent(inout) :: list(:)
    integer, intent(out)           :: marker
    integer                        :: left, right, pivot_ix
    type(CFG_var_t)                :: temp
    character(len=CFG_name_len)    :: pivot_value

    left        = 0
    right       = size(list) + 1

    ! Take the middle element as pivot
    pivot_ix    = size(list) / 2
    pivot_value = list(pivot_ix)%var_name

    do while (left < right)

       right = right - 1
       do while (lgt(list(right)%var_name, pivot_value))
          right = right - 1
       end do

       left = left + 1
       do while (lgt(pivot_value, list(left)%var_name))
          left = left + 1
       end do

       if (left < right) then
          temp = list(left)
          list(left) = list(right)
          list(right) = temp
       end if
    end do

    if (left == right) then
       marker = left + 1
    else
       marker = left
    end if
  end subroutine parition_var_list