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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 .


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

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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 2-Mar-2025

... by: Jacques Guillot, Mandeville, Louisiana

Thank you for your site - I have had unbelievable joy over years using it.

I might have overlooked it, but does your unique rectangle page have to me one of the most basic use cases? Three bivalue squares xy and one trivalue square xyz, so the trivalue square must be z.

I love unique rectangles, but I think the technique is not respected in some circles, because it is not “pure logic.” Do you have any comments?

Again, tremendous love, gratitude, and respect to you!

Jacques

Andrew Stuart writes:
Good question and thanks for the kind words ;)
Sounds like it would be captured by Type 1
But also sounds like Bi-Value Universal Grave
I disagree with the non-UR people. To be a Sudoku puzzle it must have one solution – otherwise it is a different beast and we’re not playing the same game. If so, let’s use logic

Friday 21-Feb-2025

... by: A random stranger, Earth

Der Mr. Stuart,
I've been enjoying 1 to 25 as of late. However, there are several things which I've noticed which I consider rather unfortunate:
-on mobile in portrait mode there isn't realy a way to go to other places on the site (contrary to this domain, where you can use the page Index link to find your way around)
-The Puzzles don't seem to be ordered in order of difficulty. Today, for example, Puzzles 2-4 solved pretty easy for me, while Puzzles 1 is so far unsolved.
-particularely bad together with the previous point and contrary to e.g. the sudoku player, the player for 1-25 doesn't seem to save partial progress so I can always come back later.
Kind regards, a random stranger

Andrew Stuart writes:
Good points, I will fix these
Regards the grade I don't actually know how to evaluate their difficulty. I've assumed because the puzzle is small and finite the grade range isn't huge. I do know how to test for there being one solution as that's an important puzzle criteria. But get back to me if you have grading ideas.
Edit 24-Feb: Progress saving done; CSS done to show "Page Index" on mobile

Monday 17-Feb-2025

... by: Boris, Croatia

Dear Mr. Stuart,
first I want to praise the quality and scope of the Sudokuwiki, really impressing!

I am retired, so I don't have much idle time and I limit my activity to the basic sudoku, not even the very tough, just moderate ones.

I purchase printed brochures with sudoku puzzles, enter them im your solver to print them and solve on the paper. In last several months I had problems with printing the sudoku with given numbers only, instead of printing empty cells blank, solver fills them with all nine candidates, distorting the cells.

To avoid this problem, I start solving the sudoku on-line as far as I can without writing the candidates, then choose the option "Automatically clear" and repeat the last solved candidate to obtain the real remaining candidates and then print the sudoku with them.

Can you help me with this problem? Why empty cells can't be really empty?

Once again, thank you for running this excellent site!

Kind regrds, Boris Halasz, Zagreb, Croatia

Andrew Stuart writes:
Very glad you are enjoying the site. Yes I've tried to make the print mirror the solver as much as possible. People like to set up candidates and then proceed manually. To print without candidates untick “Shown”
Send me a screen shot of anything distorted. I would love to fix that

Saturday 15-Feb-2025

... by: Yannick, Germany

Thank you so much for your Killer Sudoku Solver, just helped me after I got stuck for an hour while also teaching me something!

Andrew Stuart writes:
Very glad to hear that! Good luck wth your next one ;)

Sunday 9-Feb-2025

... by: John, Virginia

Load Sudoku:

I got stuck on this NYT sudoku so I entered it in your solver. But your solver took some steps and then got stuck looking for naked pairs/triples (it says "wait") and it is no longer possible to take any steps

Andrew Stuart writes:
Give it a go now. Works for me this morning. I am still trying to understand what causes this. Sometimes it is deliberate as when I’m replacing the binary with a new version. Sometimes the server is busy. But I’ve seent go to 100% cpu as well.

Saturday 1-Feb-2025

... by: jdrano, michigan

I love your killer Sudoku solver. I usually make a mistake because of the notes in the small squares I'm working in. I can read the notes because they are clear(better than my handwriting...lol). In general; hands down; this site is best I've worked with.

Andrew Stuart writes:
Many thanks, kind words!

Saturday 25-Jan-2025

... by: Warren Jobs, USA

import a sudoku works once for me if I use paste. when I past another it says only 29 characters entered although there were 81. the first 52 characters in line 1 are ignored. I have tried this in 3 different browsers. same results in all

Andrew Stuart writes:
Can you send me what you are trying to paste in?
Will be formats I have not anticipated.

Saturday 25-Jan-2025

... by: Nada Savatic, US

On the Sudoku solver, there are 2 buttons (Enter new killer or Modify this Killer). Pressing either button takes you to the same interface. The current killer is displayed and if you want to do a new killer, you must press the Start Over button.
Why have 2 buttons? Have one and call it Enter New/Modify this Killer.
Thanks for providing such a great tool.
Nada Savatic

Andrew Stuart writes:
Yes this actually by design. I found it was too easy to lose progress if you accidentally closed the popup or tab and rather than frustrate the user this way, I try and save it and reload it automatically. If you use “modify killer” that will fill the buffer for Work In Progress and be show when you “enter new killer”. Hence [start over]. Maybe I could change the button text if this was filled or pop up a question. Welcome any clearer UX ideas.

Thursday 23-Jan-2025

... by: Pauline, Europe

I cannot print the killer sudoku any more, neither in black and white nor in colour. There seems to be an error in uploading the sudoku to the printing format. Please help!

Andrew Stuart writes:
Found the problem on the Killer Solver page
Please refresh the Killer Sudoku page. Should now work
Daily Killer puzzle should be okay
https://www.sudokuwiki.org/Daily_Killer_Sudoku.aspx
I'm seeing a full board:
https://www.sudokuwiki.org/Players/Print_Daily_Killer.aspx?grade=2
Also use [CRTL]+[F5] in case there is a cache issue

Thursday 23-Jan-2025

... by: Barbara Hill , Near Chicago

Something is wrong with the Sudokuwiki app (Android). I have been unable to download the daily puzzle for the last two days. I just get an error message, and the puzzle list ends on Monday. Thanks for your attention.

Andrew Stuart writes:
Try again now. Did some nudging under the hood
Page:2025 1 2 3 4 5 6 7 :2024 2023 2022 2021 2020 2019 2018 2017
2015 2014 2013 2012 2011 2010 2009 2008 2007 2006
Thank-you everyone for all your questions and contributions.