day 1

day1/app/Main.hs

@@ -0,0 +1,31 @@
+module Main (main) where
+
+import System.Environment
+
+main :: IO ()
+main = do
+    path <- getArgs
+    file <- readFile $ path !! 0
+    let instructions = map  parseInput $ lines file
+    let result = foldl rotate (0, 50) instructions 
+    print result
+
+parseInput :: String -> (Rotation, Int)
+parseInput (dir:num) = (getRotation dir, read num)
+parseInput _ = error "Invalid Input"
+
+data Rotation = LEFT | RIGHT deriving (Show)
+
+getRotation :: Char -> Rotation
+getRotation 'L' = LEFT
+getRotation 'R' = RIGHT
+getRotation _ = error "Invalid Rotation"
+
+
+rotate :: (Int, Int) -> (Rotation, Int) -> (Int, Int)
+rotate (acc, pos) (RIGHT, num) = ((pos + num) `div` 100 + acc, (pos + num) `mod` 100)
+rotate (acc, pos) (LEFT, num) = let totalPos = pos - num 
+                                    offset = if pos == 0 then -1 else 0 in
+    case totalPos `mod` 100 of
+        0 -> (abs (totalPos `div` 100) + acc + 1 + offset, 0)
+        newPos -> (abs (totalPos `div` 100) + acc + offset, newPos)