Re: Arrays, slices, case, and ‘in’ strategies

[Simon Wright <simon@pushface.org>]

Simon Wright <simon@pushface.org> writes:

> Mace Ayres <mace.ayres@gmail.com> writes:
>
>> if ... OR also, the cell/record has a field with its triad, a constant
>> property.
>
> Don't understand this.

Oh, I see, it's Sudoku, and those are the given cells.

Anyway, this looks simple enough for checking whether the value is
already in the block:

   function Check_Block (For_Value : Integer;
                         At_Row : Grid_Coordinate;
                         At_Column : Grid_Coordinate;
                         In_Grid : Grid) return Boolean
   is
      Row_First : constant Grid_Coordinate := ((At_Row    - 1) / 3) * 3 + 1;
      Col_First : constant Grid_Coordinate := ((At_Column - 1) / 3) * 3 + 1;
   begin
      for Row in Row_First .. Row_First + 2 loop
         for Col in Col_First .. Col_First + 2 loop
            if In_Grid (Row, Col).X = For_Value then
               return False;
            end if;
         end loop;
      end loop;
      return True;
   end Check_Block;