Initial commit

2017/01/day1.hs

@@ -0,0 +1,18 @@
+#!/usr/bin/env stack
+-- stack --resolver lts-9.14 script
+
+sumMatchingOffset :: Int -> [Int] -> Int
+sumMatchingOffset k xs =
+  foldr (\x acc -> if fst x == snd x then acc + fst x else acc) 0 xs'
+  where n = length xs
+        xs' = zip xs (take n . drop k . cycle $ xs)
+
+toDigits :: String -> [Int]
+toDigits = map (read . (:""))
+
+main :: IO ()
+main = do
+  digitsStr <- getLine
+  let digits = toDigits digitsStr
+  putStrLn . show $ sumMatchingOffset 1 digits
+  putStrLn . show $ sumMatchingOffset (length digits `div` 2) digits