The New Sudoku Players' Forum

[Eltee27]

Hello,

I have a very quick question regarding validating that my puzzles are solved correctly.

If I check that all the rows are unique, contain only the numbers 1-9 and don't have any duplicates. Then I do the same for all the columns. Do I need to do the same for the 3x3 boxes?

Shouldn't checking the rows and columns ensure that the boxes are also correct?

[rjamil]

Hi,

Short and quick reply is "No".

You need to check the 3x3 box as well for duplication as per standard Sudoku rules, i.e.,:

"The object is to fill all empty squares so that the numbers 1 to 9 appear exactly once in each horizontal row, vertical column and 3x3 box."

R. Jamil

[JPF]

For a long reply, see here .
You need 21 checks. For instance : check all boxes , two rows in each band, and two columns in each stack.

JPF

[Eltee27]

Thank you both very much!