AoC/2022/day07/day07.hs

58 lines
1.8 KiB
Haskell

import Data.List
type Name = String
type Size = Int
data Inode = File Name Size | Folder Name [Inode] deriving Show
data ICrumb = ICrumb Name [Inode] deriving Show
type IZipper = (Inode, [ICrumb])
main :: IO ()
main = do
input <- map words <$> lines <$> readFile "input"
let fullFS = walk (tail input) ((Folder "/" []), [])
let sizeList = getDirSizeList $ upTop fullFS
print $ sum $ filter (<100000) sizeList
let toDelete = (subtract 40000000) $ getDirSize $ upTop fullFS
print $ head $ dropWhile (< toDelete) $ sort sizeList
up :: IZipper -> IZipper
up (node, ICrumb name nodes:crumbs) = (Folder name (node:nodes), crumbs)
upTop :: IZipper -> IZipper
upTop (inode, []) = (inode, [])
upTop z = upTop (up z)
newFile :: Inode -> IZipper -> IZipper
newFile node (Folder name nodes, crumbs) = (Folder name (node:nodes), crumbs)
goTo :: Name -> IZipper -> IZipper
goTo name (Folder fname nodes, crumbs) =
let (ls, node:rs) = break (nameIs name) nodes
in (node, ICrumb fname (ls++rs):crumbs)
nameIs :: Name -> Inode -> Bool
nameIs name (Folder folderName _) = name == folderName
nameIs name (File fileName _) = name == fileName
walk :: [[String]] -> IZipper -> IZipper
walk (("$":"cd":name:[]):xs) z = walk xs $ if name==".." then up z else goTo name z
walk (("$":"ls":[]):xs) z = walk xs z
walk (("dir":name:[]):xs) z = walk xs $ newFile (Folder name []) z
walk ((size:name:[]):xs) z = walk xs $ newFile (File name (read size)) z
walk _ z = z
getDirSize :: IZipper -> Int
getDirSize ((Folder _ nodes),_) = sum $ map getSize nodes
where getSize (File _ size) = size
getSize folder = getDirSize (folder,[])
getDirSize _ = 0
getDirSizeList :: IZipper -> [Int]
getDirSizeList ((Folder _ nodes),_) = getDirSize ((Folder "" nodes),[]) : concat [getDirSizeList (node,[]) | node<-nodes]
getDirSizeList _ = []