111 lines
3.6 KiB
Haskell
111 lines
3.6 KiB
Haskell
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module Day7.Main (main) where
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import System.IO
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import Data.List
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import Data.List.Split
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import Data.Char
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import System.IO.Unsafe
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import Data.Maybe
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main :: IO ()
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main = do
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putStrLn "Day 7"
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handle <- openFile "app/Day7/input" ReadMode
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contents <- hGetContents handle
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let r1 = part1 contents
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putStrLn $ "part 1: " ++ show r1
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let r2 = part2 contents
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putStrLn $ "part 2: " ++ show r2
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type Name = String
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type Size = Int
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data FileSystem = Node Name [FileSystem]
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| File Name Size
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deriving (Show)
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instance Read FileSystem where
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readsPrec _ ('d':'i':'r':' ':xs) = [(Node xs [], "")]
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readsPrec _ file = [(File name size, "")]
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where
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parts = splitOn " " file
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name = parts !! 1
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size = read $ parts !! 0
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showFileSystemWithIndent :: Int -> FileSystem -> String
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showFileSystemWithIndent n (File name size) = replicate (n*2) ' ' ++ "- " ++ name ++ " (size: " ++ show size ++ ")\n"
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showFileSystemWithIndent n (Node name files) = replicate (n*2) ' ' ++ "- " ++ name ++ "/\n" ++ concatMap (showFileSystemWithIndent (n+1)) files
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data Command = Cd Name
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| Ls [FileSystem]
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instance Show Command where
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show (Cd name) = "$ cd " ++ show name ++ "\n"
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show (Ls files) = "$ ls " ++ show files ++ "\n"
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rstrip :: String -> String
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rstrip = reverse . dropWhile isSpace . reverse
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instance Read Command where
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readsPrec _ ('c':'d':' ':name) = [(Cd name, "")]
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readsPrec _ ('l':'s':files) = [(Ls items, "")]
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where
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lines = drop 1 $ splitOn "\n" files
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items = map (read :: String -> FileSystem) lines
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parseData :: String -> [Command]
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parseData contents = map (read :: String -> Command) $ map rstrip $ drop 1 $ splitOn "$ " contents
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getName :: FileSystem -> Name
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getName (File n _) = n
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getName (Node n _) = n
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update :: Int -> a -> [a] -> [a]
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update n item ls = a ++ (item:b)
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where (a, (_:b)) = splitAt n ls
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addToFs :: FileSystem -> [Name] -> FileSystem -> FileSystem
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addToFs (Node name files) [] item = Node name (item:files)
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addToFs (Node name files) (dir:path) item = Node name files'
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where
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index = fromJust $ findIndex ((== dir) . getName) files
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file' = addToFs (files !! index) path item
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files' = update index file' files
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executeCommand :: [Command] -> [Name] -> FileSystem -> FileSystem
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executeCommand [] pwd fs = fs
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executeCommand ((Cd "/"):cs) _ fs = executeCommand cs [] fs
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executeCommand ((Cd ".."):cs) (_:pwd) fs = executeCommand cs pwd fs
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executeCommand ((Cd ".."):cs) [] fs = error "eyyy cd .. from root!"
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executeCommand ((Cd path):cs) pwd fs = executeCommand cs (path : pwd) fs
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executeCommand ((Ls files):cs) pwd fs = executeCommand cs pwd fs'
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where fs' = foldr (\i f -> addToFs f (reverse pwd) i) fs files
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commandsToFs :: [Command] -> FileSystem
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commandsToFs commands = executeCommand commands [] (Node "root" [])
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dirSize :: FileSystem -> Int
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dirSize (Node _ files) = sum $ map dirSize files
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dirSize (File _ size) = size
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bigDirs :: FileSystem -> [Int]
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bigDirs (Node _ files) = concatMap bigDirs files ++ [size]
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where size = dirSize (Node "" files)
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bigDirs (File _ _) = []
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part1 :: String -> Int
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part1 contents = sum $ filter (<= 100000) $ bigDirs results
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where
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results = commandsToFs $ parseData contents
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part2 :: String -> Int
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part2 contents = minimum candidates
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where
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results = commandsToFs $ parseData contents
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fsSize = dirSize results
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unused = 70000000 - fsSize
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needed = 30000000 - unused
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candidates = filter (>= needed) $ bigDirs results
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