Solver App for Android
Strategies for Popular Number Puzzles
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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 .

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

Monday 19-Feb-2024

... by: Lorna, England

Is it possible to create a new jigsaw sudoku in the jigsaw solver in the same way that a new killer sudoku can be created, as the jigsaw designs listed do not match the designs in the magazine I have.

Andrew Stuart writes:
I really hope to provide this soon. I need a way to pass an arbitrary map into the solver. Is near the top of my wish list for sure

Friday 16-Feb-2024

... by: Klemens Mevenkamp, Germany

Found a bug in the jigsaw solver. After elimination with the simple strategies it finds a rectangle elimination saying B1+2 forces A3+2, which is correct, but that means two 2s in box 1, not none.

Andrew Stuart writes:
Send in the example! Would love to make a correction to the solver for this situation

Wednesday 7-Feb-2024

... by: Fred Harte, Ireland

Load Sudoku:

A Penguin Pocket book contains 201 classic puzzles of which just one seems to have more than one solution according to your solver. I don't know whether this oddity is due to a misprint in the book or to a bug in the solver. I have given it here so that you can decide if it is the latter.

Andrew Stuart writes:
Check you entered the numbers right into the solver. Could be a typo there or a missing clue
If all correct, then 100% confident that is a badly made Sudoku puzzle. While it's quite easy to make a puzzle, checking it has one solution is a lot harder. Looks like they skimped!

Friday 19-Jan-2024

... by: Fanou, France

Lorsque je coche "effacement automatique des candidats", la saisie d'une solution de cellule recalcule tous les candidats et les affiche, même ceux effacés volontairement (suite à la détection de paire par exemple ).
Il faut alors re-effacer les candidats inutiles détectés aux étapes précédentes. C'est dommage !
Est il possible de remédier à ce problème?
Merci d'avance.

Andrew Stuart writes:
You need to turn off "auto clear". But "Take Step" will re-calculate. I suggest using the "Player >" button to take the puzzle to the player since that is where you can complete the puzzle manually, or stay in the solver and don't use "Take step". I don’t think it is possible to add candidates that the solver disagrees with. Hope that helps a bit

Wednesday 10-Jan-2024

... by: AnnEliza, Canada

Lettericious isn’t working it’s doubling or tripling the scores

Andrew Stuart writes:
Yes I’ve been trying to figure out why and no luck so far. I have created a system where I can re-calculate the score and overwrite, which I have done. I am checking everyday. I am probably going to have to re-write the scoring part.

Saturday 6-Jan-2024

... by: Carl, Southern California, USA

Is there a key to decoding your annotation system ?

Andrew Stuart writes:
Do you mean the longer Sudoku string format?
There is an explanation and code here

Thursday 4-Jan-2024

... by: J, Portugal

Since some days ago the mini str8ts only shows a black square, not showing the challenge

Andrew Stuart writes:
Restocked now!

Monday 1-Jan-2024

... by: Tim, USA

Would it be possible to add a button to the solver to display the current puzzle state in your new notation? It would make it easier to provide you with the exact board condition we have a question on.

You might have to assume all singles are givens.

Andrew Stuart writes:
Yes, use [Email This Board] - now shows both formats
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Thank-you everyone for all your questions and contributions.