aoc2023-1-1.hs

module Main where
import Data.ByteString qualified as BS
import Data.ByteString.Char8 qualified as BSC
import Data.Char (isDigit)

main :: IO ()
main = do
  content <- BS.readFile "input.txt"
  let lines_sep = BSC.lines content
  let x = fmap (take_first_and_last . filter isDigit) (BSC.unpack <$> lines_sep)
  print $ sum x

take_first_and_last :: [Char] -> Int
take_first_and_last [] = error "no number in this line"
take_first_and_last (x : []) = read (x : [x])
take_first_and_last (x : xs) = let l = last xs in read (x : [l])

aoc2023-1-2.hs

module Main where

import Data.ByteString qualified as BS
import Data.ByteString.Char8 qualified as BSC
import Data.Char (isDigit)
import Data.List (tails)

main :: IO ()
main = do
  content <- BS.readFile "input.txt"
  let lines_sep = BSC.lines content
  let x = fmap (process [] . concat . windows 5) (BSC.unpack <$> lines_sep)
  print $ sum x

windows :: Int -> [a] -> [[a]]
windows n = fmap (take n) . tails

process :: [Char] -> [Char] -> Int
process x ('o' : 'n' : 'e' : xs) = process (x ++ ['1']) xs
process x ('t' : 'w' : 'o' : xs) = process (x ++ ['2']) xs
process x ('t' : 'h' : 'r' : 'e' : 'e' : xs) = process (x ++ ['3']) xs
process x ('f' : 'o' : 'u' : 'r' : xs) = process (x ++ ['4']) xs
process x ('f' : 'i' : 'v' : 'e' : xs) = process (x ++ ['5']) xs
process x ('s' : 'i' : 'x' : xs) = process (x ++ ['6']) xs
process x ('s' : 'e' : 'v' : 'e' : 'n' : xs) = process (x ++ ['7']) xs
process x ('e' : 'i' : 'g' : 'h' : 't' : xs) = process (x ++ ['8']) xs
process x ('n' : 'i' : 'n' : 'e' : xs) = process (x ++ ['9']) xs
process x (i : xs) =
  if isDigit i
    then process (x ++ [i]) xs
    else process x xs
process bucket [] = take_first_and_last bucket
  where
    take_first_and_last :: [Char] -> Int
    take_first_and_last [] = error $ "no number in this line"
    take_first_and_last (x : []) = read (x : [x])
    take_first_and_last (x : xs) = let l = last xs in read (x : [l])