Feedback and Questions

That is an oversight of mine. The candidates "shown" checkbox was not being used. Untick to not print candidates

okay thanks for the report. Fixed. Might need to press [CRTL]+[F5] on the print page

Fixed this now! Thanks for the report. Yes was a change recently where I opened all grades. Thought I’d tested the print.

Send it to me and I'll take a look. Use [Email This Board]

This is a good idea. I recently added that feature to Killer Sudoku, so I will do the same for Sudoku

It is (was) documented under "Singles Chains"/ However your question does raise the further question of why I don't pick one and be consistent, so I'll do that now. Goes way way back to like 2006 or something when the Sudoku community was still naming things and different sets of people used different names. So going with "Simple Colouring"

Hi Alan
Grader working for me as of testing just now. Let me know if it stops and if there is any error message or symptom. Send the puzzle so I can check that as well.
Regards the "check solved cells" these are usually a result of a naked or hidden single which are described in the text box. I highlight the number when it goes big for easy spotting.

Hi Chris. Just tested this and can't see a fault. send another feedback or email me so I can reply personally. See if we can sort this out. Anyone else having this problem?

Passed your comment on.

Very eloquent and interesting feedback, many thanks.
My only experience of tournament Sudoku was quite a long time ago. I was briefly involved one year with the Daily Telegraph when they ran an annual competition. I was pretty downcast by the very easy puzzle they picked and couldn’t understand why they chose it. Wasn’t my pick. The competition became a speed contest, not a thoughtful one. I’m sure other contests are better.

What’s happened with the advanced strategies like colouring wasn’t driven by contests or published puzzles really. People on forums were just interested in edge case puzzles that were found to be much more difficult than the usual fare. Often these enthusiasts would go looking for them and then advance some theory. Unlike most other pattern puzzles Sudoku happens to be unusually rich – I like to think as rich as chess. Which is why I started and continued with the site. I would not get very far or have much to say about Hitori or Kakuro for example.

Much of the site is devoted to these quite abstract and complex strategies as they are mainly of interest to other puzzle software writers but there is no clear divide where pen and paper stops. Now there are some very clever people who swear they use advanced strategies on pen and paper puzzles and they certainly enjoy doing them, whatever help they really use. So there is a market for them. But don’t publish extremes in newspapers as they would frustrate most players. The diabolical needs to be quite hard though – the spectrum is wide. I think if you avoid notes you should can validly use inspiration and still crack tough puzzles.

I agree that some patterns are so hidden you are trial and erroring in your search for them. It is an open question of whether there are more transparent replacements. We’re certainly not at the end yet of guaranteeing all puzzles have a logical solution.

Does QB64 have linked lists? I find having pointers very helpful. For example placing all cells in rows, columns and boxes into the same structure is very helpful and avoids writing code specifically for a row, or a columns or a box. Then adding other constraints in (for variants) is relatively trivial. I had to do this quite early as I was asked to make Jigsaws soon after vanilla. Use bit arrays also. Need two bytes for 9 numbers sadly but worth it for candidate spreads.

Best of luck with your solver and let me know how you get on