haskell: 2015 02a

2015/haskell/app/Main.hs

@@ -1,18 +1,19 @@
+{-# LANGUAGE TypeApplications #-}
 module Main where
 
-import Text.Printf (printf)
 import qualified Day01
+import qualified Day02
 import qualified Day03
+import Text.Printf (printf)
 
 readDay :: Int -> IO String
 readDay n = readFile $ getPath n
  where
-    getPath n = "../.inputs/" <> printf "%02d" n <> ".txt"
+  getPath n = "../.inputs/" <> printf "%02d" n
-
 
 main :: IO ()
 main = do
-  content <- readDay 3
+  content <- readDay 2
-  let parsed = Day03.parse content
+  let parsed = Day02.parse content
-  print $ Day03.solve1 parsed
+  print $ Day02.solveA parsed
-  print $ Day03.solve2 parsed
+  print @Int $ Day02.solveB parsed

2015/haskell/haskell.cabal

@@ -1,18 +1,15 @@
 cabal-version: 3.0
-name:               haskell
+name: aoc2015
 version: 0.1.0.0
 synopsis: Advent of Code 2015 solutions
-
 -- A longer description of the package.
 -- description:
 homepage:
-
 -- A URL where users can report bugs.
 -- bug-reports:
 license: MIT
 author: Maciej Jur
 maintainer: maciej@kamoshi.org
-
 -- A copyright notice.
 -- copyright:
 -- category:
@@ -21,28 +18,26 @@ extra-source-files: CHANGELOG.md
 library
   exposed-modules:
     Day01
+    Day02
     Day03
 
   -- Modules included in this library but not exported.
   -- other-modules:
-
   -- LANGUAGE extensions used by modules in this package.
   -- other-extensions:
-    build-depends:    base ^>=4.16.4.0
+  build-depends: base >=4.16.4.0
-    hs-source-dirs:   src
+  hs-source-dirs: solutions
   default-language: Haskell2010
 
 executable haskell
   main-is: Main.hs
-
   -- Modules included in this executable, other than Main.
   -- other-modules:
-
   -- LANGUAGE extensions used by modules in this package.
   -- other-extensions:
   build-depends:
-        base ^>=4.16.4.0,
+    base >=4.16.4.0,
-        haskell
+    aoc2015,
 
   hs-source-dirs: app
   default-language: Haskell2010

2015/haskell/solutions/Day01.hs

@@ -1,10 +1,9 @@
 module Day01 (parse, solve1, solve2) where
 
 import Data.Char (isPrint)
-import Data.List (scanl, findIndex)
+import Data.List (findIndex, scanl)
 import Data.Maybe (fromJust)
 
-
 parse :: String -> String
 parse = filter isPrint
 
@@ -21,4 +20,3 @@ solve2 :: String -> Int
 solve2 = fromJust . findIndex (< 0) . scanl reducer 0
  where
   reducer acc next = acc + mapper next
-

2015/haskell/solutions/Day02.hs

@@ -0,0 +1,30 @@
+module Day02 (parse, solveA, solveB) where
+
+splitOn :: (Eq a) => a -> [a] -> [[a]]
+splitOn _ [] = []
+splitOn delimiter xs =
+  let (before, remainder) = break (== delimiter) xs
+   in before : case remainder of
+        [] -> []
+        _ : rest -> splitOn delimiter rest
+
+parse :: String -> [(Int, Int, Int)]
+parse = map toTuple . lines
+ where
+  toTuple :: String -> (Int, Int, Int)
+  toTuple str = let [a, b, c] = splitOn 'x' str in (read a, read b, read c)
+
+toArea :: (Int, Int, Int) -> Int
+toArea (l, w, h) =
+  let a = l * w
+      b = w * h
+      c = h * l
+   in 2 * a + 2 * b + 2 * c + min a (min b c)
+
+solveA :: [(Int, Int, Int)] -> Int
+solveA = sum . map toArea
+
+-- >>> map toArea $ parse "2x3x4"
+-- [64]
+
+solveB = undefined