# Puzzle No. 280, 281 : Regional Yajilin, Antidiagonal Sums Sudoku

Daily league update :

On Saturday, Bram posted a No 10 Sudoku. Kwaka came up with an innovative variant called Mickey Mouse on Sunday. Fred posted a tricky Extra Regions Sudoku yesterday, and here is my contribution below. Oh and the combined Week 2 PDF has been released, and is publicly available here, with the usual target solve times for different levels of solvers.

Coming to the blog post now, I have had Sudokucup 9 hanging over my head through the weekend, and so the reason for the delay in posting. I thought I’d make it up by posting 2 puzzles again. My week  3 of the Daily League went really well and I’m leading that week for now, although its still open for solving and adding your time on the spreadsheet that can be found on our facebook group. The lead up being so good, I was hoping for a good showing in Sudokucup 9, and thankfully I had that, even if I did keep putting it off for not being in the best of health. I finished at 8th place.

The Regional Yajilin is a reject from one of the many other sets I’m working on. It might be tricky if you’re not familiar with looping techniques but should go along fine otherwise. The Antidiagonal Sums Sudoku isn’t too tricky.

For 280 : Follow Regional Yajilin rules. Some loop segments are given.

For 281 : Follow regular Sudoku rules. Additionally, each of the main diagonals must contain exactly 3 distinct digits. One digit is the sum of the other two.

Enjoy!

P280

P281

## 5 comments on “Puzzle No. 280, 281 : Regional Yajilin, Antidiagonal Sums Sudoku”

1. TheSubro

Fantastic regional Yajilin. Loved every step of it. Thanks.

TheSubro

2. ArDeeJ

Are the numberless (Yajilin) regions empty or do they contain an indeterminate amount of shaded cells?

I’ve been stuck on it for a while. Any hints on where to stare at?

• They contain an indeterminate amount of cells. Its better to just think of them as the places not having any added constraints due to the regions (kinda like a normal Yajilin has cells not pointed to by any arrow but the cells can still be shaded).

For hints – look at the 3×4 region where you’ve basically elminated the top row as far as shaded cells go. You can eliminate some more cells there, methodically. Also, the possibilities for the extreme right region is very limited, even if the region is big, that might help later on in the solve.

• ArDeeJ

Thanks! I had almost deduced the contents of the 3*4 box, I don’t know why I didn’t realise that I knew where two of the filled cells had to be.

The rest of the solve flowed really nicely, I agree with TheSubro, lovely puzzle. ❤

That was my first regional Yajilin (and I've solved about three normal Yajilins), that was great practise.

3. skynet

15:53.Took quite a bit of time on that but lovely puzzle with a nice theme !