From 4d486b471c9ac8943b5bd6595b4544d2d07d95a6 Mon Sep 17 00:00:00 2001
From: Yuchen Pei <me@ypei.me>
Date: Sat, 9 Dec 2017 21:49:43 +0100
Subject: attempted part 2 of puzzle 7

---
 Puzzle7.hs | 56 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 56 insertions(+)

diff --git a/Puzzle7.hs b/Puzzle7.hs
index 9010dd0..00dae27 100644
--- a/Puzzle7.hs
+++ b/Puzzle7.hs
@@ -1,5 +1,7 @@
 import Data.Set (toList, (\\), fromList)
 import Data.List.Split (splitOn, splitOneOf)
+import Data.Map (Map)
+import qualified Data.Map as Map
 
 parseInput :: [Char] -> [[Char]]
 parseInput xs = filter (elem '>') (splitOn "\n" xs)
@@ -18,6 +20,60 @@ solve1FromPair (xs, ys) = head $ toList $ (fromList xs) \\ (fromList ys)
 
 solve1 :: [Char] -> [Char]
 solve1 = solve1FromPair . g . f . parseInput
+
+parseLine xs = (node, (weight, children))
+  where node:weight:children = splitOneOf ",()-> " xs
+
+parseInput' xs = Map.fromList . (fmap parseLine) . (splitOn "\n") xs
+
+update nodes weights node
+  | null children = Map.insert node weight weights
+  | otherwise = fromJust . Map.lookup $ foldl (newWeights nodes) weights children
+    where (weight, children) = fromJust . Map.lookup node nodes
+
+newWeights nodes weights node = 
+  if member node weights 
+    then weights
+    else update nodes weights node
+
+findAnomaly xs 
+  | null ys  = Nothing
+  | length ys > 1 = Just $ fst $ head xs
+  | otherwise = Just $ fst $ head ys
+    where ys = filter (\z -> snd z /= snd head xs) xs
+
+
+solve2' nodes node weight
+  fst $ until (isNothing . snd) badChild (root, Just root)
+  where 
+    root = solve1 input
+    badChild x
+      | isNothing $ snd x = x
+      | otherwise = findAnomaly (\z -> (z, fromJust $ Map.lookup z weights)) <$> (snd . fromJust . Map.lookup y) nodes
+        where y = fromJust . snd x
+
+
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+
 
 input0 = "pbga (66)\nxhth (57)\nebii (61)\nhavc (66)\nktlj (57)\nfwft (72) -> ktlj, cntj, xhth\nqoyq (66)\npadx (45) -> pbga, havc, qoyq\ntknk (41) -> ugml, padx, fwft\njptl (61)\nugml (68) -> gyxo, ebii, jptl\ngyxo (61)\ncntj (57)"
 
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