87 lines
2.5 KiB
Haskell
87 lines
2.5 KiB
Haskell
{-# LANGUAGE OverloadedStrings #-}
|
|
|
|
import Data.Either (rights)
|
|
import Data.Text (Text)
|
|
import qualified Data.Text as T (head, lines, words)
|
|
import qualified Data.Text.Read as T (decimal)
|
|
import Data.Tree
|
|
import Lib (readFile')
|
|
|
|
-- this solution assumes that empty directories can exist,
|
|
-- if you want to ignore that, there is a slightly different code in day7'.hs
|
|
|
|
-- needs cleaning and improvement, although i like the fact
|
|
-- that the entire FS can be printed as a tree
|
|
|
|
main :: IO ()
|
|
main = do
|
|
tree <- snd . flip parse (emptyFs "/") . map T.words . T.lines <$> readFile' "day7.in"
|
|
putStr "Q1: "
|
|
print $
|
|
foldTree
|
|
( \x xs ->
|
|
if null xs || snd x > 100000 then sum xs else snd x + sum xs
|
|
)
|
|
tree
|
|
putStr "Q2: "
|
|
let maxStorage = 70000000
|
|
let spaceNeeded = 30000000 - (maxStorage - snd (rootLabel tree))
|
|
print $
|
|
foldTree
|
|
( \x xs ->
|
|
if snd x < spaceNeeded
|
|
then minimum (maxStorage : xs)
|
|
else minimum (snd x : xs)
|
|
)
|
|
tree
|
|
|
|
type Filesystem = Tree (Text, Int)
|
|
|
|
tail' :: [a] -> [a]
|
|
tail' = drop 1
|
|
|
|
-- wrapper to create an empty tree
|
|
emptyFs :: Text -> Filesystem
|
|
emptyFs n = Node (n, 0) []
|
|
|
|
-- This function is to replace a filesystem by name
|
|
-- Used to replace empty directories with parsed directories in code
|
|
replaceFs :: Filesystem -> Text -> Filesystem -> Filesystem
|
|
replaceFs (Node n xs) name fs =
|
|
let (h, t) = span ((/= name) . fst . rootLabel) xs
|
|
in Node
|
|
(fst n, snd n + snd (rootLabel fs))
|
|
(h ++ [fs] ++ tail' t)
|
|
|
|
-- Sum of all filesystems in the list
|
|
-- Used to calculate sum of leaves in code
|
|
totalSize :: [Filesystem] -> Int
|
|
totalSize = sum . map (snd . rootLabel)
|
|
|
|
-- All directories/files are parsed here into leaves
|
|
ls :: [[Text]] -> [Filesystem]
|
|
ls =
|
|
map
|
|
( \[a, b] ->
|
|
if a == "dir"
|
|
then Node (b, 0) []
|
|
else Node (b, fst . head $ rights [T.decimal a]) []
|
|
)
|
|
|
|
-- main function where stuff happens
|
|
parse :: [[Text]] -> Filesystem -> ([[Text]], Filesystem)
|
|
parse input fs
|
|
| null input || cur == ["$", "cd", ".."] = (tail' input, fs)
|
|
| cur == ["$", "ls"] =
|
|
let (children, rest) = span ((/= "$") . head) (tail' input)
|
|
leaves = ls children
|
|
name = fst $ rootLabel fs
|
|
in parse rest (Node (name, totalSize leaves) leaves)
|
|
| otherwise =
|
|
let name = cur !! 2
|
|
(nextInput, newFs) = parse (tail' input) (emptyFs name)
|
|
replaced = replaceFs fs name newFs -- replace empty directory
|
|
in parse nextInput replaced
|
|
where
|
|
cur = head input
|