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Feedback and Questions

I've received a lot of interesting comments and questions from Sudoku fans over the last few years and this page is where I try to answer them. I'm also directing Str8ts feedback here. Please feel free to drop me a note on the side of the page. Or you can email me directly at andrew@str8ts.com.

Post a Comment or Question here...

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Any Sudoku you want to publish here for easy loading into the solver - Either 81 numbers or the packed string version.

	public - comment/question will be added to feedback column
	private - email comment/question directly to Andrew Stuart, don't display here

Comment, question or feedback:

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If you are writing to alert me of a problem (thank-you!) please include a url to the page in question.
Can get fixes in quicker if I know immediately where to go.

Many thanks to all the people who have helped improve the solvers and strategies with their feedback!

Sunday 24-Nov-2019

... by: Shelli, Washington, DC (USA)

Thank you SO MUCH for the new secure site! You can't image how worried I was about the FBI monitoring my Sudoku activity. ;-)

Andrew Stuart writes:

I know, just don't get radicalized. :0

Sunday 24-Nov-2019

... by: Michael, Germany

Dear Andrew,

my Sudoku Android App doesn't download the daily puzzles anymore. Is this because you moved your site to HTTPS?

Regards Michael

Andrew Stuart writes:

That's possible, maybe doesn't like the 301 redirect. It should not care but that's apps. However, last night I found a way to put the /feed part onto http alone. Any problem today?

Thursday 21-Nov-2019

... by: DUANE RAEBURN, usa

Can I use your solver to do cell logic ( only these numbers can go here) and box logic ( this number can here or here)? I hope that is clear. This is a nice site and thank you for all the work you have done on this.

Andrew Stuart writes:

Do you mean, no constraints on rows and columns? Just cells and boxes?
Sounds like a Magic Square
Currently, no, not in the solver as set up

Saturday 16-Nov-2019

... by: Håkan Holgersson, Sverige

Hello Andrew Stuart! Wonderful site! Thanks!

Andrew Stuart writes:

Thanks Håkan!

Wednesday 13-Nov-2019

... by: Pat, United States

Have you taken your website down? It seems broken. I hope not, I have enjoyed using it for years! It sure helps when you get stuck on a puzzle.

Andrew Stuart writes:

Server is tempremental and I am in the process of porting to a new one.

Monday 11-Nov-2019

... by: Phil Turner, England

Load Sudoku: CLICK TO LOAD

This sudoku appeared on "Cracking the Cryptic" and is not solvable by your programme. However, it can be solved using just hidden/naked digits and wings, if wings is extended beyond jellyfish. Do you consider wings greater than 4 by 4 to be unusable in practice? Best wishes, Phil.

Andrew Stuart writes:

This puzzle found a bug in the Gurth detection. It caused 5 to map to 0 which screwed everything up. Now fixed. If you manually add 5 into the center cell E5 it will be a gurth puzzle and some detections are made. Either way it solves relatively, mainly with X-wings

I believe the 5x5 extension of a Jelly-Fish is called as Squirm-Bag. But it is redundant since if it exists then a corresponding 4x4 Jelly-Fish will exist and that should be used instead.

Saturday 2-Nov-2019

... by: Matthew Kim, United States

https://www.telegraph.co.uk/news/science/science-news/9359579/Worlds-hardest-sudoku-can-you-crack-it.html

how difficult would you say this REALLY is? i did, in fact, complete it, and it definitely wasn't easy, but I'd like to hear an opinion from you

Andrew Stuart writes:

See Arto Inkala Sudoku

Wednesday 30-Oct-2019

... by: Fred, south east US

Load Sudoku: CLICK TO LOAD

The solver on the web page gives an erroneous answer after just now step on A5 as 8.9, and at I5 as 8,9. It should be 1,8 for both. Thanks, Fred

Andrew Stuart writes:

Seems okay to me but 1 and 9 in those cells.

Friday 4-Oct-2019

... by: Nigri, India

i am new to difficult sudoku. Learning new techniques. i didnt know about a 3�3�3 swordfish only 2x2x2. Your trick helped me solve a puzzle. I have been stuck for weeks. Thanks

Andrew Stuart writes:

Excellent!

Thursday 3-Oct-2019

... by: Annie, NZ

Such a brilliant tool! Best on the net, has helped me learn so many techniques, thank you so much! Any chance you're developing a Kakuro Solver?

Andrew Stuart writes:

Thanks so much, very kind.
I can make Kakuro puzzles so I can solve them, so internally I do have a solver. But I've found that there are not many special strategies so its of much less interest than, say, Sudoku. It would just munch through them rather than explaining anything very clever.

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Thank-you everyone for all your questions and contributions.