### Even/Odd Sudoku by Thomas Snyder

or solve online (using our beta test of Penpa-Edit tools)

**Theme:** Bull’s-Eye

**Author/Opus:** This is the 218th puzzle from Thomas Snyder, aka Dr. Sudoku.

**Rules:** Standard Even/Odd Sudoku rules (i.e., cells with a square contain an even digit; cells with a circle contain an odd digit).

**Answer String:** Enter the 2nd row from left to right, followed by a comma, followed by the 7th row from left to right.

**Time Standards (highlight to view):** Grandmaster = 9:00, Master = 21:00, Expert = 42:00

**Solution:** PDF; a solution video is available here.

**Note:** Follow this link for more Even/Odd Sudoku puzzles. If you are new to this puzzle type, here are our easiest Even/Odd Sudoku to get started on. More Even/Odd Sudoku puzzles can be found in *The Art of Sudoku 2*.

I found the evens quite challenging. What was I supposed to be seeing to help me get going with them?

The even path is definitely challenging. Focus on 2 and 4 and after placing a couple digits, there is an unusual elimination in column 3 with one of those digits.

Impressive arragement of givens and even / odd cells.

Thanks. These are exactly my kind of puzzles. I had some trouble finishing the even digits, but having marked all cells as odd/even I knew it was just a matter of finding the right trick.

Did you find this layout of even digits so it would work with only 4 givens before setting up the whole puzzle or was that a lucky coincidence? For me it was just luck to find out my 5 even givens in the layout in my Battenburg Sudoku would lead to a unique solution.

I may have gotten a little lucky in playing with configurations here to get just four even givens to work. I started with one each of 1-9 (one per box) about where they sit now and with the 9,8 flip to get asymmetry. Most of my work was then going through a lot of possible center ring patterns and the position of the 4 and 6 clues before hitting this grid which only needed some extra 5’s to get to one answer.

The solving path is hard for the puzzles I publish here, but that it cleanly hides a skyscraper/coloring step in just even digits made it feel like a fair way to push the envelope for a Saturday.

I think it’s always fairer to have those steps when there are fewer digits involved. There’s a real difference between a skyscraper step that opens up a puzzle at the start or that closes off a puzzle at the end.

33:24.Never thought that I would be guessing in an even/odd to take it to completion.

Don’t feel bad, I had to guess in the end as well. Had all the evens/odds marked out and for some reason I was actually able to solve all of the odds logically but could NOT get the evens, I’m not sure what logical step I missed. I don’t even know how much time this one took me as I was just kinda poking at it for a couple minutes at a time at various times, but it’s been sitting in a tab for several days at least.

I mean, I thought it was a great puzzle but I just got sick of staring at it 🙂

Could someone explain what a skyscraper step is? I was able to solve the evens by simple coloring. Did i miss something easier? A really outstanding puzzle, I did not think it was possible for an even/odd puzzle to be so hard but very very fun!

Here is one spot to see a description. Simple Coloring will often reveal the same kinds of eliminations as a Skyscraper.