mass rename

Signed-off-by: Amneesh Singh <natto@weirdnatto.in>

day07.hs

@@ -0,0 +1,86 @@
+{-# 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