Solving the NY Times "Pips" game with F#
12 comments
·October 23, 2025sunrunner
This is great, and serendipitous timing for me.
After spending an embarrassing amount of time on today's hard before I went to bed I was wondering what kind of metrics could go into analysing the difficulty of any Pips game (and which ones NYT Games uses) and whether it would be worth writing a solver to do this analysis. I was also considering an SMT or CP approach instead of backtracking as an alternative.
Edit: And after looking through the solve times in more detail, I feel vindicated that the hard for today (01/11/2025) was both a single solution and took the solver over 8x as long to find the solution. It took me longer than 8x my average, but that's besides the point...
ematth
Hey Brian, I really enjoyed reading your work on the Pips game! I found myself applying a similar backtracking algorithm to my Pythonic solution (https://github.com/ematth/pips). I focused on finding a single solution for each puzzle as opposed to all possible solutions. For hard puzzles with longer run times, I found that running multiple processes, each with the domino list shuffled, gets the solve time down to <15 seconds.
brianberns
Thanks! I'm glad to see I'm not the only one who went down this rabbit hole. :)
I considered parallelizing my solution as well, but the problem is that it only gives a linear speedup, while the problem space increases exponentially. I decided to focus on pruning the search tree instead, and that seemed to work pretty well (after much thinking).
prb
It's getting crowded down here in the rabbithole... One more to peek at: https://github.com/prb/pips-solver/blob/main/README.md
tzs
Last updated 2025-10-27.
[...]
The puzzles with the most solutions are:
• 2025-09-15 hard: 2,764,800 solutions
• 2025-10-05 hard: 344 solutions
• 2025-09-30 hard: 110 solutions
• 2025-09-04 hard: 86 solutions
• 2025-08-23 hard: 80 solutions
munchler
That's great! Your experience with the 2025-09-15 and 2025-10-14 puzzles was very similar to mine, I think. I'm impressed that you were able to get AI models to solve this game effectively. I coded it the old-fashioned way myself, mostly, with occasional help from Gemini Pro.
eszed
I really enjoy the Pips game, but it doesn't appear on the games page in my (Android) NY Times app. I'm a subscriber, and the app is up to date. I can get to it by searching for the article announcing it a few months back, and then clicking through from there, and it works just fine.
Presumably it's there in the separate NYT Games app, but I'd rather not install a separate app.
Does anyone know why they exclude it from the regular games section? I realize this is the silliest of all first-world problems, but still: Why?
atombender
It's in the separate Games app. I believe Pips isn't a "full" member of the games section yet (it has no archive, leaderboard or achievement badges), which is probably why they're not including it.
IshKebab
I quite like this game but it does feel a little like I'm a human SAT solver.
lloydatkinson
Pretty cool! I used backtracking for a very similar layout problem: generating word searches. I used C# for that.
Looks like quite a few people who have written Pips solvers are here. I too have one (a dumb as a rock brute force solver in C).
How are you all getting the puzzles into your solvers? I just found out that the puzzles are available in JSON at https://www.nytimes.com/svc/pips/v1/YYYY-MM-DD.json
where YYYY-MM-DD is the date for the puzzle. They have past puzzles and even some future puzzles. At the moment they through 2025-11-25.
Right now I'm using a hand written text input that for example looks like this:
for the 2025-09-09 easy puzzle which looked like this: Those JSON downloads are going to make things so much more convenient!