[Day 05] Part 2: Oh yeah this is simple was overthinking it

1 files changed, 21 insertions, 1 deletions

diff --git a/day05/day05.hs b/day05/day05.hs
index 9118cd2..5c589e7 100644
--- a/day05/day05.hs
+++ b/day05/day05.hs
@@ -23,6 +23,12 @@ valid :: [Rule] -> Update -> Bool
 valid rules update =
   all (abides update) $ filter (relevant update) rules
 
+apply :: [Rule] -> Int -> Int -> Ordering
+apply rules a b
+  | [a,b] `elem` rules = LT
+  | [b,a] `elem` rules = GT
+  | otherwise = EQ
+
 part11 :: Int -> [Rule] -> [Update] -> Int
 part11 acc _ [] = acc
 part11 acc rules (h:t)
@@ -33,6 +39,20 @@ part1 :: [Rule] -> [Update] -> Int
 part1 rules updates =
   part11 0 rules updates
 
+part21 :: Int -> [Rule] -> [Update] -> Int
+part21 acc _ [] = acc
+part21 acc rules (h:t)
+  | valid rules h = part21 acc rules t
+  | otherwise =
+    let rrules = filter (relevant h) rules
+        sfun = apply rrules
+        inc = middle $ sortBy (sfun) h in
+          part21 (acc + inc) rules t
+
+part2 :: [Rule] -> [Update] -> Int
+part2 rules updates =
+  part21 0 rules updates
+
 main = do
   file <- readFile "day05.input"
   let lns = lines file
@@ -40,4 +60,4 @@ main = do
       rules = map (map (read::String->Int)) $ map (splitOn "|") rulesin
       updates = map (map (read::String -> Int)) $ map (splitOn ",") updatesin
   putStrLn ("Part 1: " ++ (show $ part1 rules updates))
-  --putStrLn ("Part 2: " ++ (show $ part2 fst sec))
+  putStrLn ("Part 2: " ++ (show $ part2 rules updates))