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