... by: Bob Spessard, USA

Why are pointing pairs down the difficulty list. They seem to be much easier to spot than hidden pairs and triples?
Andrew Stuart writes (23-Nov-2008):
The order of the strategies is only roughly in order of complexity, there's a certain amount of user preference and that’s my list. I'd like to offer the chance of re-ordering them but it’s a bit of a programming job. So I don't disagree with you

... by: Paul, London, England

Using your Sudoku assistant in Google Chrome it is not possible, after using the mouse to start the solution process, to then use the enter key to step through the remaining steps in the solution. The mouse must be used for all the steps - very tedious. Because of this I revert to IE5 when I need your wonderful tool, such as the Diabolical sudoku in yesterday's Daily Telegraph.
Andrew Stuart writes (22-Nov-2008):
I've just downloaded Chrome to confirm this problem. Previously was replying on user reports who said the solver worked fine in Chrome. I've done some research and testing - its not the page, its definitely a short coming with the browser. Button simple do not show focus when you have focus on them. Nor does enter key activate them. I hope they fix it with the next release. It is a very new browser. Thanks for the alert

... by: suchita chaturvedi, india,asia

ur site is amazing.I've made a project on sudoku solver only with the help of ur site. It helps me a lot.It gives a very good idea about how the puzzle is solved stepwise.iI want to thank u as much as possible. THANK UUUUUUUUUUUUUUUUU

... by: Pat Williams, USA

Load Sudoku: None

I liked your site.
Andrew Stuart writes (14-Nov-2008):
thx!

... by: gkelly, layton, ut

Load Sudoku: .......6.28......4..7..58..5..34..2.4..5.1..8.1..76..3..51..2..3......81.9.......

I thought I understood coloring until your solved showed how to eliminate a 4 at H4 but showing a chain at C2,A3,C4,H3 how is it that from this you know to remove 4 from H4?
Andrew Stuart writes (19-Oct-2008):
Ok its an off-chain elimination. Chain is H3->A3->C2->C4 and the reverse. Both ends can see H4 and both ends are difference color - so one with be a 4. so H4 can't be That help?

... by: Geoff, Australia

Load Sudoku: 601000725592617438000520619810050962359862147026000853160205394203496501945000206

Hi, Andrew. This is a great site-it has turned me into a sudoku fanatic. I'm confused about x-cycles where strong links are considered weak. Can all strong links be considered weak when convenient to achieve candidate elimination? In the above puzzle your solver eliminates 7 at d3 as it has weak links to f1 and g3. I think f1-d3 is strong. Why am I wrong? Anyway, its all great fun. Geoff
Andrew Stuart writes (4-Oct-2008):
You are right, have a look at the bottom section of this page: http://www.scanraid.com/X_Cycles_Part_2 I explain all there

... by: RL Purple, UAS, Minnesota

Thank you.
You have given a retired old professor a lot of insights and pleasure on taking up this hobby.
Andrew Stuart writes (4-Oct-2008):
Thank you sir! My pleasure Best of luck Andrew Stuart

... by: Larry orrick, U S

Would like to suggest you offer the option to print the "possibilities" along with the puzzle after buying the Puzzle Pack. This would save time as I don't like the job of doing that busy work.
Thanks
Larry
Andrew Stuart writes (29-Sep-2008):
I've thought of that as well. It would not be appropriate for gentle or moderate puzzles since it would give away too many solved cells, but for diabolical and extremes, it might work. It would mean doubling up the puzzle packs or making them twice the size. That could be done if there was sufficient demand. Otherwise, I could provide a text file with the puzzles to link to the solver, Take Step once would give you the same effect

... by: John Robinson, Western North Carolina

Would it be possible to make the daily sudoku saveable and to be able to print out the puzzle plus the possible candidates that I have inserted?
Thank You, JR
Andrew Stuart writes (24-Sep-2008):
You can use the Email This Board function to save your sudoku at any stage of solving. Follow the instructions to copy into an email message and send the message to yourself.

... by: Mats Anderbok, Sweden

Load Sudoku: .3...............9..95............2....1......2....63......6..8.5..32.....7.4...1

It may be time to replace your brute force solution counter with a more efficient algorithm. It works fine in most cases, but the worst case is terrible. The maximum number of recursions for a valid sudoku is probably 15-30 billion, which is about a thousand times more than your counter can handle before is produces a "timed out" error.

Solving singles first and then bi-value cells reduces the number of recursions considerably (but each recursion takes longer time). I will include a counter is the next version of my own solver (Java applet), but I haven't decided yet how to implement it.

The example is a permutation of no. 32632 from Gordon Royle's list (of 47793 puzzles with 17 given) which requires 14,724,893,706 recursions.

Andrew Stuart writes (24-Sep-2008):
Yes, the brute force algorithm could definitely be improved by having it solve as many squares as possible using basic strategies before applying the brute force approach. Your example solves completely using basic strategies, but times out using "Solution Count." As a workaround for the time out error, until "Solution Count" is made more efficient, I suggest using "Take Step" to solve a few squares and then try Solution Count again.

... by: PaulyPitts, New Jersey, USA

Would it be possible to add a button that would yield the instant puzzle solution ready for printout? While I'm working on a puzzle, like to verify my individual square solutions to check on my work. I also find this very instructive because it gives me instant feedback if my logic is faulty. If there was one button to click that would present the solved puzzle for printing, it would be of great help.

By the way, your Sudoku site is the very best. It just keeps on getting better and better. Keep up the good work.

PaulyPitts
Andrew Stuart writes (24-Sep-2008):
I don't plan to add an "Instant Solution" button. However, click "Solution Count" and copy the solution string. Open a second solver window and click Import a Sudoku. Paste the string and click OK. Click either the Print 1 or Print 2 button and then print the page with the solution. Lastly, thanks for the compliment!