RegEx Crossword
11 comments
·October 28, 2025a022311
hdjrudni
I like that one better. Smaller. More manageable. I don't want to spend 2 hours deciphering the big one.
Took 4.5 min to solve #519. Would have been quicker if I started with a better strategy but it was my first time.
hughes
519 seems to have at least 3 solutions... feels a little underconstrained!
Levitating
I got #520 in 3m 8s with some practice on the big one.
I thought the bigger one was more fun though, I'll continue with that one now.
padolsey
For something a bit simpler I made redoku a while ago: https://padolsey.github.io/redoku/
Levitating
It seems impossible?
On the left a horizontal must start with F: F.[AO].[AO].*
However, the diagonal for that cell may not include an F (aside from the start): [^X]*(DN|TE|NI)
rzwitserloot
BIG EDIT:
Because it's so trivially unsolvable, I had a quick look at the posted solution.
We're reading it wrong.
Take the first regex on the top row, one you included in your example:
[^X]*(DN|TE|NI)
You're supposed to fill that in from the bottom to the top.
In other words, the first letter goes immediately to the right of [^c]*[^R]*III.* - that square has to be a 'not X'. The hex immediately below it has to be an E, I, or N.
glxxyz
[^X] means any character other than X, so [^X]* matches zero or more of any characters, so long as none of them are X.
Levitating
Ah my bad! I did misinterpret [^X] as X or the line-start.
throwaway019254
[^X]* means anything but X as many times as you want. So F will match this part.
mcpherrinm
https://blog.nelhage.com/post/regex-crosswords-z3/ was posted a few days ago here and is an interesting way to solve these
Yesterday, I discovered regexle [1] and today found out that this was the inspiration for it.
I think I've seen this puzzle before, but I really enjoyed myself gradually solving it while doing other things in the last two hours. I'm sharing this for anyone else who wants a way to spend their afternoon!
[1]: https://regexle.com