adventofcode/2022/app/Day3/Main.hs

module Day3.Main (main) where

import System.IO
import Data.Char
import Data.List.Split

main :: IO ()
main = do
    putStrLn "Day 3"
    
    handle <- openFile "app/Day3/input" ReadMode
    contents <- hGetContents handle

    let r1 = part1 contents
    putStrLn $ "part 1: " ++ show r1

    let r2 = part2 contents
    putStrLn $ "part 2: " ++ show r2

type Rucksack = (String, String)

parseData :: String -> [Rucksack]
parseData input = zip firstCompartments secondCompartments
    where
        rucksacks = lines input
        compartmentSize = map ((`div` 2) . length) rucksacks
        firstCompartments = map (uncurry take) (zip compartmentSize rucksacks)
        secondCompartments = map (uncurry drop) (zip compartmentSize rucksacks)

inBoth :: Eq a => [a] -> [a] -> [a]
inBoth a b = [x | x <- a, y <- b, x == y]

allEqual :: Eq a => [a] -> Bool
allEqual []     = True
allEqual (x:xs) = all (== x) xs

inAll :: Eq a => [[a]] -> [a]
inAll xs = map ((!! 0) . snd) res
    where
        prod = sequence xs
        equal = map allEqual prod
        res = filter fst (zip equal prod)

getValue :: Char -> Int
getValue a | a >= 'a' && a <= 'z' = ord a - ord 'a' + 1
getValue a | a >= 'A' && a <= 'Z' = ord a - ord 'A' + 1 + 26

part1 :: String -> Int
part1 contents = sum values
    where
        both = map (uncurry inBoth) (parseData contents)
        single = map (!! 0) both
        values = map getValue single

part2 :: String -> Int
part2 contents = sum values
    where
        groups = chunksOf 3 (lines contents)
        badges = map ((!! 0) . inAll) groups
        values = map getValue badges