🌉 - 2024 DAY 7 SOLUTIONS - 🌉

Day 7: Bridge Repair

Megathread guidelines

Keep top level comments as only solutions, if you want to say something other than a solution put it in a new post. (replies to comments can be whatever)
You can send code in code blocks by using three backticks, the code, and then three backticks or use something such as https://topaz.github.io/paste/ if you prefer sending it through a URL

FAQ

What is this?: Here is a post with a large amount of details: https://programming.dev/post/6637268
Where do I participate?: https://adventofcode.com/
Is there a leaderboard for the community?: We have a programming.dev leaderboard with the info on how to join in this post: https://programming.dev/post/6631465

53 comments

Uiua
This turned out to be reasonably easy in Uiua, though this solution relies on macros which maybe slow it down.
(edit: removing one macro sped it up quite a bit)
(edit2: Letting Uiua build up an n-dimensional array turned out to be the solution, though sadly my mind only works in 3 dimensions. Now runs against the live data in around 0.3 seconds.)
Try it here
undefined

Data ← ⊜(□⊜⋕⊸(¬∈": "))⊸≠@\n "190: 10 19\n3267: 81 40 27\n83: 17 5\n156: 15 6\n7290: 6 8 6 15\n161011: 16 10 13\n192: 17 8 14\n21037: 9 7 18 13\n292: 11 6 16 20" Calib! ← ≡◇⊢▽⊸≡◇(∈♭/[^0]:°⊂) # Calibration targets which can be constructed from their values. &p/+Calib!⊃(+|×)Data &p/+Calib!⊃(+|×|+×ⁿ:10+1⌊ₙ₁₀,)Data
- I feel like I need a Rosetta stone to read this code
  
  Here you go
- Thanks to your solution I learned more about how to use reduce :D
  My solution did work for the example input but not for the actual one. When I went here and saw this tiny code block and you saying
  This turned out to be reasonably easy
  I was quite taken aback. And it's so much better performance-wise too :D (well, until part 2 comes along in my case. Whatever this black magic is you used there is too high for my fried brain atm)
  
  Haha, sorry about that, it does seem quite smug :-) I went into it expecting it to be a nightmare of boxes and dimensions, but finding it something I could deal with was a massive relief. Of course once I had a working solution I reversed it back into a multi-dimensional nightmare. That's where the performance gains came from: about 10x speedup from letting Uiua build up as many dimensions as it needed before doing a final deshaping.
  I enjoyed reading a different approach to this, and thanks for reminding me that ⋕$"__" exists, that's a great idiom to have up your sleeve.
  Let me know if there's any bits of my solution that you'd like me to talk you through.

Haskell
A surprisingly gentle one for the weekend! Avoiding string operations for concatenate got the runtime down below one second on my machine.
undefined

import Control.Arrow import Control.Monad import Data.List import Data.Maybe readInput :: String -> [(Int, [Int])] readInput = lines >>> map (break (== ':') >>> (read *** map read . words . tail)) equatable :: [Int -> Int -> Int] -> (Int, [Int]) -> Bool equatable ops (x, y : ys) = elem x $ foldM apply y ys where apply a y = (\op -> a `op` y) <$> ops concatenate :: Int -> Int -> Int concatenate x y = x * mag y + y where mag z = fromJust $ find (> z) $ iterate (* 10) 10 main = do input <- readInput <$> readFile "input07" mapM_ (print . sum . map fst . (`filter` input) . equatable) [ [(+), (*)], [(+), (*), concatenate] ]
- Love the fold on the list monad to apply the operations.
- Since all operations increase the accumulator, I tried putting a guard (a <= x) in apply, but it doesn't actually help all that much (0.65s -> 0.43s).
  
  0.65 -> 0.43 sounds pretty strong, isn't that a one-fourth speedup?
  Edit: I was able to achieve a 30% speed improvement using this on my solution
- I wanted to this the way yo did, by repeatedly applying functions, but I didn't dare to because I like to mess up and spend some minutes debugging signatures, may I ask what your IDE setup is for the LSP-Hints with Haskell?
  Setting up on my PC was a little bit of a pain because it needed matching ghc and ghcide versions, so I hadn't bothered doing it on my Laptop yet.
  
  I use neovim with haskell-tools.nvim plugin. For ghc, haskell-language-server and others I use nix which, among other benefits makes my development environment reproducible and all haskellPackages are built on the same version so there are no missmatches.
  But, as much as I love nix, there are probably easier ways to setup your environment.
  
  Ah, well, I have a bit of a weird setup. GHC is 9.8.4, built from git. I'm using HLS version 2.9.0.1 (again built from git) under Emacs with the LSP and flycheck packages. There are probably much easier ways of getting it to work :)

53 comments

Day 7: Bridge Repair

Megathread guidelines

FAQ

Uiua

Haskell