Day 6

src/Day2506.hs

@@ -0,0 +1,54 @@
+module Main where
+
+import Data.List (find, transpose)
+import Data.Maybe (isNothing, isJust)
+
+splitPred :: (a -> Bool) -> [a] -> [[a]]
+splitPred _ []  = []
+splitPred f str | isNothing $ find f str = [str]
+                | otherwise              = takeWhile (not . f) str : splitPred f (drop 1 $ dropWhile (not . f) str)
+
+part1 :: String -> Int
+part1 = sum . map calcOne . transpose . parser 
+  where
+  parser :: String -> [[String]]
+  parser = map splitLine . lines
+    where
+    splitLine :: String -> [String]
+    splitLine = filter (not . null) . words
+
+  calcOne :: [String] -> Int
+  calcOne xs = foldl1 operation operands
+    where
+    operation = if last xs == "+" then (+) else (*)
+
+    operands :: [Int]
+    operands = map read $ drop 1 $ reverse xs
+  
+
+part2 :: String -> Int
+part2 = sum . map (calcOne . transpose) . parse
+  where
+  parse = splitPred (all (==' ')) . transpose . lines
+
+  calcOne :: [String] -> Int
+  calcOne xs = foldl1 operation operands
+    where
+    operation = getOperation xs
+    operands = getOperands xs
+
+    getOperands :: [String] -> [Int]
+    getOperands xs = map read $ transpose operands
+      where
+      operands = take (length xs - 1) xs
+
+    getOperation :: [String] -> (Int -> Int -> Int)
+    getOperation xs = if isJust $ find (=='+') $ last xs then (+) else (*)
+
+
+main :: IO ()
+main = do
+  str <- getContents
+
+  print $ part1 str
+  print $ part2 str