Day 6

2019/day6/day6.hs

@@ -0,0 +1,21 @@
+import Data.List.Split
+import Data.List
+import Data.Maybe
+
+main = do
+    content <- (map (splitOn ")") . lines) <$> readFile "input"
+    print $ day6a content
+    print $ day6b content
+
+day6a l = sum $ map (day6a' (transpose l) l) l
+day6a' l l2 (s:t)
+    | s `elem` (l!!1)=1+day6a' l l2 (l2 !! (fromJust (elemIndex s (l!!1))))
+    | otherwise=1
+
+day6b :: [[String]] -> Int
+day6b l = day6b' l "YOU" "SAN" [] - 2
+day6b' l s t visited
+    | [s,t]`elem`l||[t,s]`elem`l=1
+    | otherwise = 1 + minimum [if x `elem` visited then maxBound -1 else day6b' l x t (x:visited)| x<-neighbours s]
+    where neighbours a = filter (/=a) $ concat
+            [if x==a then xs else [] | xs<-l, x<-xs]