Day 4: Scratchcards
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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
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I had to give Uiua another go today. (run it here)
{"Card 1: 41 48 83 86 17 | 83 86 6 31 17 9 48 53"
"Card 2: 13 32 20 16 61 | 61 30 68 82 17 32 24 19"
"Card 3: 1 21 53 59 44 | 69 82 63 72 16 21 14 1"
"Card 4: 41 92 73 84 69 | 59 84 76 51 58 5 54 83"
"Card 5: 87 83 26 28 32 | 88 30 70 12 93 22 82 36"
"Card 6: 31 18 13 56 72 | 74 77 10 23 35 67 36 11"}
LtoDec ← ∧(+ ×10:) :0
StoDec ← LtoDec▽≥0. ▽≤9. -@0
# Split on spaces, drop dross, parse ints
≡(⊜□≠0.⊐∵(StoDec)↘ 2⊜(□)≠@\s.⊔)
# Find matches
≡(/+/+⊠(⌕)⊃(⊔⊢↙ 1)(⊔⊢↙¯1))
# part 1
/+ⁿ:2-1 ▽±..
# part 2 - start with matches and initial counts
=..:
# len times: get 1st of each, rotate both, add new counts
⍥(⬚0+↯: ⊙⊙∩(↻1) ⊙:∩(⊢.))⧻.
/+⊙;
Nim
This one was pretty simple, just parse the numbers into sets and check the size of the intersection. Part 2 just made the scoring mechanism a little more complicated.
Hi there! Looks like you linked to a Lemmy community using a URL instead of its name, which doesn’t work well for people on different instances. Try fixing it like this: !nim@programming.dev
That’s some elegant code! Then again, I suppose that’s the beauty of nim.
I’m rather spoiled by python, so I feel like it could be more elegant. xD
But yeah, I do like how this one turned out, and nim runs a whole lot faster than python does. I really like nim’s “method call syntax”. Instead of having methods associated with an individual type, you can just call any procedure as x.f(remaining_args) to call f with x as its first argument. Makes it easy to chain procedures. Since nim is strongly typed, it’ll know which procedure you mean to use by the signature.
Aside from the general conciseness, the “universal function call syntax” is my favorite aspect of nim.
If you want to take chaining procedures to the next level, try a concatenative language like Factor (I have a day 4 solution in this thread – with no assignment to variables).
I also suggest having a look at Roc if you want a functional programming adventure, which offers great chaining syntax, a very friendly community, and is in an exciting development phase.
LANGUAGE: Nim
Welcome to the advent of parsing!
Took me a lot more time than it should (Please, don’t check prior commits 😅).
Haskell
11:39 – I spent most of the time reading the scoring rules and (as usual) writing a parser…
import Control.Monad
import Data.Bifunctor
import Data.List
readCard :: String -> ([Int], [Int])
readCard =
join bimap (map read) . second tail . break (== "|") . words . tail . dropWhile (/= ':')
countShared = length . uncurry intersect
part1 = sum . map ((\n -> if n > 0 then 2 ^ (n - 1) else 0) . countShared)
part2 = sum . foldr ((\n a -> 1 + sum (take n a) : a) . countShared) []
main = do
input <- map readCard . lines <$> readFile "input04"
print $ part1 input
print $ part2 input
