Day 1

01/silver.hs

@@ -0,0 +1,21 @@
+
+import Data.List -- sort
+
+mapTuple :: (a -> b) -> (a, a) -> (b, b)
+mapTuple f (a1, a2) = (f a1, f a2)
+
+-- helper function for split
+splitH :: [a] -> [a] -> [a] -> ([a], [a])
+splitH ls rs (x:xs) = splitH rs (ls++[x]) xs
+splitH ls rs _ = (ls, rs)
+
+-- split: split list into two by alternating between left and right
+split :: [a] -> ([a], [a])
+split = splitH [] []
+
+-- calculates the sum of the absolute distance between two lists
+dist :: Int -> ([Int], [Int]) -> Int
+dist acc (l:ls, r:rs) = dist (acc + abs (r - l)) (ls, rs)
+dist acc _ = acc
+
+main = interact $ show . dist 0 . mapTuple sort . split . map (read :: String -> Int) . words