Refactor code

src/Day12.hs

@@ -0,0 +1,45 @@
+module Day12 (day12_1) where
+
+import Data.Foldable (toList)
+import Data.Graph (Tree, Vertex, graphFromEdges, scc)
+import Data.List (uncons)
+import Data.List.Split (chunksOf)
+import Data.Maybe (fromJust)
+
+type Coords = (Int, Int)
+
+type V = (String, Int)
+
+getValue :: [[V]] -> Coords -> V
+getValue grid (i, j) = grid !! i !! j
+
+getEdges :: [[V]] -> Coords -> [Int]
+getEdges grid (i, j) =
+  let value = fst $ grid !! i !! j
+      adjI = filter (\x -> fst x >= 0 && fst x < length grid && snd x >= 0 && snd x < length (fst . fromJust $ uncons grid)) [(i, j + 1), (i + 1, j), (i, j - 1), (i - 1, j)]
+   in [snd x | x <- map (getValue grid) adjI, (fst . fromJust $ uncons value) == (fst . fromJust $ uncons (fst x))]
+
+listVertices :: [String] -> [[V]]
+listVertices grid =
+  let l = length $ fst . fromJust $ uncons grid
+   in chunksOf l $ zip (map (: []) (concat grid)) [0 ..]
+
+calculatePerimeter :: (Vertex -> (String, Vertex, [Vertex])) -> Tree Vertex -> Int
+calculatePerimeter nodeFromVertex p =
+  let edges = concat [x | (_, _, x) <- toList $ fmap nodeFromVertex p]
+      area = 4 * length p
+   in area - length edges
+
+day12_1 :: IO ()
+day12_1 = do
+  contents <- lines <$> readFile "input/day12.txt"
+  let grid = listVertices contents
+      edgeCoords = [(x, y) | x <- [0 .. length grid - 1], y <- [0 .. length (fst . fromJust $ uncons grid) - 1]]
+      edgeList = [(x, y, z) | ((x, y), z) <- zip (concat grid) (map (getEdges grid) edgeCoords)]
+      (graph, nodeFromVertex, _) = graphFromEdges edgeList
+      plots = scc graph
+      areas = map length plots
+      perimeters = map (calculatePerimeter nodeFromVertex) plots
+  putStrLn $
+    "Day 12, Puzzle 1 solution: "
+      ++ show (sum $ zipWith (*) areas perimeters)