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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 - 81 characters, use '.' or '0' for unknowns.

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Comment, question or feedback:

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letters you see:

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!

Tuesday 27-Aug-2024

... by: Wayne, Wales, UK

Load Sudoku: CLICK TO LOAD

Hi Andrew,

I'd just like to highlight that while solving the above puzzle, it uses simple coloring - twice in a unit. The rule states - "that if any unit has the same colour twice ALL those candidates which share that colour must be OFF.
Step 18 - Simple Colouring

(RULE 2): Two 3s in a single unit (in Col 4) have the same color in cells E4 H4 - all yellow coloured candidates can be removed
Last candidate, 9, in F7 changed to solution
Last candidate, 9, in H4 changed to solution
Last candidate, 9, in J9 changed to solution

The alternative colour will be ON and the solution for that cell. " the solver removes all instances of the yellow 3's , but does not take advantage of the fact that all the purple 3's are true.
Wayne

Andrew Stuart writes:

Yes that’s one way to think about it. Been a long while but I’ve always approached the strategies from the pov of chipping away at candidates and hoping that will reveal a solution – and mostly that’s the way they work. This rule does go direct to solutions. The mechanism for return data back to the solver is subtractive – a list of candidates to remove. So it’s a little more mechanistic than a human. Might figure out a tweak when I go back into simple colouring gain.

Sunday 25-Aug-2024

... by: AeroBB, UK

am on a mac mini running latest os/software using safari - on print 2 button getting error no parameters passed. few days ago all worked fine, not knowingly updated anything recently

Andrew Stuart writes:

Definitely the browser cache. Both request the same script file and I've set the version to be the same.

Saturday 24-Aug-2024

... by: Bellm, USA

Load Sudoku: CLICK TO LOAD

Your new print function is not working correctly. When I load this and do two clicks to eliminate possibles based on the clues, J7 should be a "1" but when I print it, it shows it as solved. Hope this makes sense. It did not used to do this.

Andrew Stuart writes:

In the solver editing a single note immediately changes to a solved cell. However in between two take-steps on a fresh board it is possible to get a single note.

It is true the old print would carry this over as a candidate. But the old way confused some people since, in certain circumstances, it would refuse to draw the board at all. This is because the print page read the opener page directly but if the opener page disappeared, or multiple tabs, or refreshed, the print page would lose its data. Took a very long time to figure out this was happening. And this method was in response to a previous method which passed all the data on the url parameter but this broke in some situations because a) great length and b) the numbers were delimited by commas and in many email programs successive commas broke automatic hyperlinks. So this inspired the ‘packed string’.

The new method passing the packed string is problematic as well since it is designed for the solver and one number in a cell signifies a solved cell. I am loath to change the format of this string since it would invalidate all the packed strings in existence. One needs a solution that is backwards compatible. So my solution is to rely on context. Since I control the function to pack the string at that point and draw the print page I’m reusing the clue flag, which is irrelevant to the print page, to flag that a single number is a note and not a solution. Voila:

link

Saturday 24-Aug-2024

... by: Terje L erstein, Norway

Lot of trouble with print option lately. Now print 1 and print 2 does not work at all

Andrew Stuart writes:

Okay I just spotted that. Bug is 10 minutes old. :)
Please also [CTRL]+[F5]. I will update the version number to bump this.

Saturday 24-Aug-2024

... by: Ineke, Eurpe

Re: new Daily Killer Jigsaw

What an excellent addition to your daily puzzles. Though I regularly play both Killers and Jigsaws, it took me some time to adjust to the format. Which is good. Keep the little grey cells doing what they're meant to do.
Thanks for this attractive new suduko.

Andrew Stuart writes:

Fantastic, kind words, thank-you

Saturday 24-Aug-2024

... by: Ineke, Europe

My compliments for the improvement on navigating. Though I didn't like the old versions, the daily killers in the weekend are frequently real killers, so I kept coming back.

Andrew Stuart writes:

Cheers! And glad you like the UI updates, always dicey changing something that been up for ages

Friday 23-Aug-2024

... by: Gepi, Australia

Load Sudoku: CLICK TO LOAD

At clues+solved 25/81, the Solver states:
Rectangle Elimination
If +3[G9] then -3[H9] forcing +3[H7] which removes all 3s from box 6, so G9 cannot be 3.
But if G9=3, H7 cannot be 3 (same box).
Moreover, G9 cannot be 3 as G12 only have 3 in box 7 !
Bug?...
jp

Andrew Stuart writes:

Update: Issue fixed. Was a bad flag, pointing pairs all the way now.

Thursday 22-Aug-2024

... by: Scott B, United States

When show candidates is checked or un-checked, all candidates are showing when using the print 1 or print 2 button.

Thanks, you have an awesome website!!

Andrew Stuart writes:

Fixed now. [CRTL]+[F5] to refresh
and thanks!

Wednesday 21-Aug-2024

... by: a random stranger, Earth

Load Sudoku: CLICK TO LOAD

Just a quick note, loading sudoku puzzles from a URL appears to have broken this morning. Only parts of the clues will load in, and a seemingly random pattern (but static for each unique puzzle) of non-clue cells will load in blank.

Sample URL:https://www.sudokuwiki.org/sudoku.htm?bd=000090050080000000607100039206000007000002000700940060000200090009005002502730046

Andrew Stuart writes:

Thanks! Fixed now. Appreciate the heads up

Monday 19-Aug-2024

... by: B Lane, US

The print option is not working. Shows o0nly the borders. Love your website.

Andrew Stuart writes:

Has been an update this morning, first try [CRTL]+[F5]. If not, send me the URL. Many print places could be.

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Thank-you everyone for all your questions and contributions.