AoC/2023/day09/day09.hs

import Control.Arrow

main :: IO ()
main = do
  input <- parse <$> readFile "input"
  print $ (day09 &&& day09 . map reverse) input

parse :: String -> [[Int]]
parse = map (map read . words) . lines

day09 :: [[Int]] -> Int
day09 =
  sum .
  map (sum . map last . takeWhile (not . null) . iterate (zipWith (-) =<< tail))
day09 2023-12-09 17:05:01 +01:00			`import Control.Arrow`

			`main :: IO ()`
			`main = do`
			`input <- parse <$> readFile "input"`
more day09 golfing p2 is just reverse p1 lol 2023-12-09 18:41:37 +01:00			`print $ (day09 &&& day09 . map reverse) input`
day09 2023-12-09 17:05:01 +01:00
			`parse :: String -> [[Int]]`
			`parse = map (map read . words) . lines`

more day09 golfing p2 is just reverse p1 lol 2023-12-09 18:41:37 +01:00			`day09 :: [[Int]] -> Int`
day09 2023-12-09 17:05:01 +01:00			`day09 =`
more day09 golfing p2 is just reverse p1 lol 2023-12-09 18:41:37 +01:00			`sum .`
			`map (sum . map last . takeWhile (not . null) . iterate (zipWith (-) =<< tail))`