# Latin square puzzle

This is a sudoku-esque puzzle I came up with when trying to solve some harder sudoku.

The rules

1. It’s a Latin square like sudoku, so there must be the numbers 1-9 exactly once in every row and column.

Numbers can be repeated in a 3x3 box with the following restrictions on rows.

Notice that each 3x3 box divides a row (1x9) into three 1x3 boxes.

1. In every row, within a 1x3 box, you can only have one number from each triple {123}, {456},{789}.

So essentially in a row you have to space out the numbers 1,2,3 into the three divisions of the row.

Eg, in the first row, the first 1x3 box contains a ‘3’, therefore in the next two boxes you cannot have a ‘1’ or a ‘2’.

There should be a unique solution from the construction.

Note: It’s only really the vertical dark lines which divide up the rows that are important, the horizontal ones are more there to make it easier to look at and for me to make the puzzle.

## 1 Answer

Nice puzzle. After getting over the sudoku preconceptions, this may even be a bit easier, since two digits in a 1x3 block rule out 6 digits already, so the row- an columnwise sudoku solving gets pretty easy.

Since this was an introductory puzzle, it was probably designed to be quite easy; didn't have to resort to anything fancier than "this square must be one of those", "this row/column needs these, how to fit them" and "this row's/column's that number cannot be anywhere else"

Shutting off the sudoku mindset was really hard in the beginning, the "only one digit missing in the square, go get it" impulse is surprisingly strong, for me at least. Future versions (I hope there will be many!) would do well to not highlight the non-meaningful 3x3 square borders.

EDIT: just in case you want to make many, many more of these, I hacked together a vector graphic (read: unlimited resolution) grid for these puzzles. If you download it, rename the file to "grid.svg", and put it on a white background, it should look something like this:

In case you want to tweak it to better suit your needs, I also uploaded the script I used to generate the image.

• I can make a harder one if you like :) thanks for trying it out! Mar 24, 2018 at 17:32
• Here’s a follow up question, I might not have time to make any today though :) Mar 24, 2018 at 18:35