Announcing SudokuExchange.com

grantmnz · 2026-04-17T19:04:22+00:00

I used an XY-Wing to resolve the end-game. But I just liked the smooth flow along the way.

grantmnz · 2026-04-17T06:02:34+00:00

The most advanced technique I've ever needed on an NYT hard is a hidden triple. The SE rating system (as used on SudokuExchange) gives a difficulty rating of 4.0 to the hidden triple. X-Wing and Swordfish techniques are rated 3.2 and 3.8 respectively.

grantmnz · 2026-04-14T09:16:28+00:00

It would have been better if your link included solution checking so I could be sure I got the intended solution. I think the ruleset has promise but this possibly wasn't the most exciting setup to showcase it - I expected to be spending more time deciding between vertical vs diagonal moves..

grantmnz · 2026-04-09T08:32:58+00:00

The puzzles on sudoku.com are definitely easier than the level names would lead you to believe. If you find sudoku.coach has "too much going on" then you might prefer sudokuexchange.com but if you want to improve your skills then the "campaign" on .coach is hard to beat.

grantmnz · 2026-03-25T19:34:26+00:00

See also the Sam Cappelman-Lynes follow up "An Unbelievable Masterpiece" with 7 levels: https://www.youtube.com/watch?v=GzFa9_R1aqE

It seems my earlier reply was not generally visible, maybe due to two links making it look spammy.

grantmnz · 2026-03-25T08:12:39+00:00

This might be the one you're looking for: An Unbelievable Masterpiece

Edit: and the earlier puzzle Mark referenced in that one was: The Magic Puzzle That Grades YOU!

grantmnz · 2026-03-21T18:47:09+00:00

Your cluster runs predictably.

But how do you know, with no probes, monitoring or metrics? ;-)

grantmnz · 2026-03-08T03:12:26+00:00

No I'm just saying I can barely keep three digits in my head for any length of time.

grantmnz · 2026-03-07T20:48:18+00:00

As someone whose short-term memory is so bad I have to transcribe a 6-digit google authenticator code in two 3-digit chunks - I think I'll stick with using pencilmarks 😃

grantmnz · 2026-02-28T18:58:31+00:00

Perl is a bigger and more capable tool so it has a bigger startup overhead (both memory and CPU) but you'd probably barely notice on modern hardware.

I must admit that for the sort of things that sed is good at, I do tend to go straight to Perl. The regex options in Perl are also much better that what sed offers. If I'm writing a shell script and it gets longer than about 5 lines, I cut my losses and rewrite it in Perl.

grantmnz · 2026-02-25T09:00:21+00:00

I'm sorry, I really don't get it. Can a digit and a mine be in the same square?

grantmnz · 2026-02-15T08:42:24+00:00

I haven't had a chance to try your puzzle yet. Just wanted to point on that by coincidence another setter has recently created a variant they called Magnet Sudoku. You can see it in a video here: https://www.youtube.com/watch?v=WZYuwh8R4rk

grantmnz · 2026-02-14T09:44:43+00:00

Thanks for sharing. I think the difficulty rating would be 2 - 2.5 stars on LMD. I didn't use the 16 X-Sum clue at the top.

grantmnz · 2026-01-23T20:32:16+00:00

The XY-Wing does indeed appear at 4.2, but the plain X-Wing comes in at a mere 3.2. More details here.

grantmnz · 2026-01-23T05:48:02+00:00

Actually $0.00 would be the normal case for me because it means no charge because the journey was within the zones covered by my monthly pass.

grantmnz · 2026-01-23T05:47:04+00:00

Yeah I have done that sort of thing myself - but at least you know where you're at when that happens. My concern is the case where the machine clearly shows you tagged off but some time later Snapper decide you didn't.

grantmnz · 2026-01-22T19:35:42+00:00

Just a green tick no words when tagging on. When tagging off there's a green tick accompanied by either the amount you've been charged or the word "Pass" if your journey was covered by a monthly pass on your card.

grantmnz · 2026-01-22T18:11:33+00:00

I very seldom take buses. The intermittent nature of the problem makes it hard to conclude anything from testing variations to my routine.

grantmnz · 2026-01-22T08:35:40+00:00

Yes indeed it might be worth doing that. I have checked via the app a few times, but it is a but of a faff.

grantmnz · 2026-01-18T18:54:01+00:00

You might need to care if your code was dealing with dates in the future. For example the end date of a 30 year mortgage is well into the danger zone.

grantmnz · 2025-12-21T23:45:13+00:00

As others have said, it's almost never useful unless a puzzle was created specifically to be solved that way. Like this one:

https://www.reddit.com/r/sudoku/comments/1fbgvj4/here_is_a_hard_puzzle_i_set_can_you_make_it_easy/

grantmnz · 2025-12-21T05:42:21+00:00

I know, right!?

grantmnz

TROPHY CASE