From de19878331f10e04c1f9599a482111bb3e7f2762 Mon Sep 17 00:00:00 2001
From: tomsmeding <tom.smeding@gmail.com>
Date: Mon, 11 Dec 2017 10:04:19 +0100
Subject: Day 11

---
 2017/11.hs | 30 ++++++++++++++++++++++++++++++
 1 file changed, 30 insertions(+)
 create mode 100644 2017/11.hs

(limited to '2017/11.hs')

diff --git a/2017/11.hs b/2017/11.hs
new file mode 100644
index 0000000..19fe862
--- /dev/null
+++ b/2017/11.hs
@@ -0,0 +1,30 @@
+import Control.Monad
+import Data.Char
+import qualified Data.Map.Strict as Map
+import Data.Map.Strict ((!))
+
+splitOn :: Eq a => a -> [a] -> [[a]]
+splitOn c xs = case break (== c) xs of
+    (pre, []) -> [pre]
+    (pre, _ : post) -> pre : splitOn c post
+
+strip :: String -> String
+strip = dropWhile isSpace . reverse . dropWhile isSpace . reverse
+
+dirmap :: Map.Map String (Int, Int)
+dirmap = Map.fromList [("n", (0,2)), ("ne", (1,1)), ("se", (1,-1)), ("s", (0,-2)), ("sw", (-1,-1)), ("nw", (-1,1))]
+
+add :: (Int, Int) -> (Int, Int) -> (Int, Int)
+add (a,b) (c,d) = (a + c, b + d)
+
+distance :: (Int, Int) -> Int
+distance (0,0) = 0
+distance (0,y) = abs y `div` 2
+distance (x,0) = abs x
+distance (x,y) = let m = min (abs x) (abs y) in m + distance (x - m * signum x, y - m * signum y)
+
+main :: IO ()
+main = do
+    input <- liftM (map (dirmap !) . splitOn ',' . strip) (readFile "11.in")
+    print $ distance $ foldl1 add input
+    print $ maximum $ map distance $ scanl add (0,0) input
-- 
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