Day 2: Red-Nosed Reports
Megathread guidelines
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FAQ
- What is this?: Here is a post with a large amount of details: https://programming.dev/post/22323136
- 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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Haskell
Had some fun with arrows.
import Control.Arrow
import Control.Monad
main = getContents >>= print . (part1 &&& part2) . fmap (fmap read . words) . lines
part1 = length . filter isSafe
part2 = length . filter (any isSafe . removeOne)
isSafe = ap (zipWith (-)) tail >>> (all (between 1 3) &&& all (between (-3) (-1))) >>> uncurry (||)
where
between a b = (a <=) &&& (<= b) >>> uncurry (&&)
removeOne [] = []
removeOne (x : xs) = xs : fmap (x :) (removeOne xs)
1 point