The New Sudoku Players' Forum

[Steerpike58]

I'm new to Sudoku and loving it. After solving a bunch of 'medium' puzzles in my local paper with ease, and after reading / practicing with hidden and naked doubles, triples, quads, and more, I'm eager to start taking on some more difficult puzzles.

I went to the site Thonky.com, and noticed they offer 'difficulty graded' puzzles, and their 'harder' categories are Moderate, Hard, Very Hard, Extremely Hard. I first tried a 'hard', and then a 'very hard', and sailed through both of them without using any 'advanced' technique other than naked pairs. Looking at other sites, it dawned on me that the 'grading' appears very subjective / site-specific (Sudoku9x9.com uses 'High School', 'College', 'Graduate' for example).

SO -

1. Is there any sort of official or accepted grading system? I see some very sophisticated references on this site to 'difficulty', but I have no idea what they mean.
2. Is there a correlation between grading and techniques - I'm currently eager to explore doubles/triples/quads, but not so much XY-chains, Skyscrapers, etc
3. Is there a site where I can plug in a 'difficulty level' (or 'technique level') and find puzzles to solve? (other than 'thonky.com', which seems a bit arbitrary)

My challenge at the moment is, while I can clearly follow and understand an example of an (eg) hidden triple, when I'm presented with an actual puzzle, I'm not sure if I'm simply failing to see an (eg) hidden triple, or the candidates presented represent a more complex scenario.

Finally, is there any site that will auto-generate the 'candidate numbers' for empty cells? I'm finding that step a bit tedious and error prone and it would be nice to automate it. I'm probably using bad terminology here; what I mean is, if you have 135|468|... in a row, then the three last cells would have 'candidates' 2,7,9; 2,7,9; 2,7,9 'penciled in'. There are plenty of sites that let you enter the 'candidates' manually, but none of them seem to validate your entries.

Hope this makes sense! Thanks in advance.

[Leren]

The two sites I usually recommend are Andrew Stuart's solver here or the Hodoku site here.

You can download the Hodoku software, which has an electronic solver with heaps of options when you get used to it. Both sites also have excellent graphical worked examples of move types.

Leren

[Pat]

auto-generate the 'candidate numbers' for empty cells:
paulspages.co.uk/sudoku/

for grading, try SuDoku Explainer...

[Steerpike58]

auto-generate the 'candidate numbers' for empty cells:
paulspages.co.uk/sudoku/

BRILLIANT - that's exactly what I was hoping for! Site looks good in general, too.

for grading, try SuDoku Explainer...

I presume you are referring to this - https://sourceforge.net/projects/sudoku-explainer/

Thanks! Very helpful!

The two sites I usually recommend are Andrew Stuart's solver here or the Hodoku site here.

You can download the Hodoku software, which has an electronic solver with heaps of options when you get used to it. Both sites also have excellent graphical worked examples of move types.

Leren

I had found the Hodoku site, and will look at the solver. Andrew Stuart's solver looks fantastic! Thanks!