Day 10

Day10.hs

@@ -0,0 +1,33 @@
+module Day10 where
+import System.IO (openFile, IOMode (ReadMode), hClose, hGetContents)
+import Data.Maybe (mapMaybe)
+
+closing :: Char -> Char
+closing '(' = ')'
+closing '[' = ']'
+closing '{' = '}'
+closing '<' = '>'
+
+score :: Char -> Int
+score ')' = 3 
+score ']' = 57
+score '}' = 1197
+score '>' = 25137
+
+
+matchBraces :: [Char] -> [Char] -> Maybe Char
+matchBraces _ [] = Nothing
+matchBraces acc (x:xs)
+    | x `elem` ['(', '[', '{', '<'] = matchBraces (closing x : acc) xs
+    | x == head acc = matchBraces (tail acc) xs
+    | otherwise = Just x 
+
+main :: IO ()
+main = do
+    input <- openFile "inputs/10.txt" ReadMode
+    contents <- hGetContents input
+
+    let routes = lines contents
+    print . sum . map score $ mapMaybe (matchBraces []) routes
+
+    hClose input

Day10_1.hs

@@ -0,0 +1,35 @@
+module Day10_1 where
+import System.IO (openFile, IOMode (ReadMode), hClose, hGetContents)
+import Data.Maybe (mapMaybe)
+import Data.List (sort)
+
+closing :: Char -> Char
+closing '(' = ')'
+closing '[' = ']'
+closing '{' = '}'
+closing '<' = '>'
+
+score :: Char -> Int
+score ')' = 1
+score ']' = 2
+score '}' = 3
+score '>' = 4
+
+
+matchBraces :: [Char] -> [Char] -> Maybe [Char]
+matchBraces []  [] = Nothing
+matchBraces acc [] = Just acc
+matchBraces acc (x:xs)
+    | x `elem` ['(', '[', '{', '<'] = matchBraces (closing x : acc) xs
+    | x == head acc = matchBraces (tail acc) xs
+    | otherwise = Nothing
+
+main :: IO ()
+main = do
+    input <- openFile "inputs/10.txt" ReadMode
+    contents <- hGetContents input
+
+    let routes = lines contents
+    print . (\x -> x !! (length x `div` 2)) . sort $ map (foldl (\acc x -> score x + (acc * 5)) 0) $ mapMaybe (matchBraces []) routes
+
+    hClose input