Refactor code

src/Day13.hs

@@ -0,0 +1,67 @@
+{-# OPTIONS_GHC -Wno-type-defaults #-}
+
+module Day13
+  ( day13_1,
+    day13_2,
+  )
+where
+
+import Data.Char (isDigit)
+import Data.Either (fromRight)
+import Data.List (uncons)
+import Data.List.Split (chunksOf, splitOn)
+import Data.Matrix (Matrix, fromLists, rref, toList, zero)
+import Data.Maybe (fromJust, mapMaybe)
+
+isAlmostInt :: (RealFrac a) => a -> Bool
+isAlmostInt x =
+  let diff = x - fromInteger (round x)
+   in abs diff < 0.001
+
+multRes :: (Num a) => [a] -> [a]
+multRes [x, y, z] = [x, y, z + 10000000000000]
+multRes xs = xs
+
+getMatrix :: (Read a) => String -> Matrix a
+getMatrix s =
+  let nValues = map (map read . splitOn ",") . splitOn ":" . drop 1 $ filter (\x -> isDigit x || x == ',' || x == ':') s
+      eq1 = map (fst . fromJust . uncons) nValues
+      eq2 = map last nValues
+   in fromLists [eq1, eq2]
+
+getMatrix' :: (Num a, Read a) => String -> Matrix a
+getMatrix' s =
+  let nValues = map (map read . splitOn ",") . splitOn ":" . drop 1 $ filter (\x -> isDigit x || x == ',' || x == ':') s
+      eq1 = multRes $ map (fst . fromJust . uncons) nValues
+      eq2 = multRes $ map last nValues
+   in fromLists [eq1, eq2]
+
+solve :: (RealFrac a) => Matrix a -> Maybe [a]
+solve eqSystem =
+  let rowEchelonList = toList . fromRight (zero 1 1) $ rref eqSystem
+      solutions = [rowEchelonList !! 2, rowEchelonList !! 5]
+   in if all isAlmostInt solutions
+        then Just solutions
+        else Nothing
+
+cost :: [Int] -> Int
+cost [x, y] = 3 * x + y
+cost _ = 0
+
+day13_1 :: IO ()
+day13_1 = do
+  contents <- map concat . chunksOf 4 . lines <$> readFile "input/day13.txt"
+  let eqSystems = map getMatrix contents
+      solutions = (map . map) round $ mapMaybe solve eqSystems
+  putStrLn $
+    "Day 13, Puzzle 1 solution: "
+      ++ show (sum $ map cost solutions)
+
+day13_2 :: IO ()
+day13_2 = do
+  contents <- map concat . chunksOf 4 . lines <$> readFile "input/day13.txt"
+  let eqSystems = map getMatrix' contents
+      solutions = (map . map) round $ mapMaybe solve eqSystems
+  putStrLn $
+    "Day 13, Puzzle 2 solution: "
+      ++ show (sum $ map cost solutions)