day 16: naive solution that obviously doesn’t work

2022/day16/day16.hs

@@ -0,0 +1,32 @@
+import Control.Lens
+import Data.List.Split
+import qualified Data.Map as M
+
+type Valves = M.Map String Node
+
+type Node = (Int, [String])
+
+main :: IO ()
+main = do
+  input <- map words . lines <$> readFile "testinput"
+  print $ parse input
+  print $ walk 5 "AA" $ parse input
+
+parse :: [[String]] -> Valves
+parse = M.fromList . concatMap parse'
+  where
+    parse' (_:name:_:_:rate:_:_:_:_:ts) =
+      [(name, (0, ("open" ++ name) : nexts)), ("open" ++ name, (r, nexts))]
+      where
+        r = read $ init $ last $ splitOn "=" rate
+        nexts = map (\(x:y:_) -> [x, y]) ts
+
+-- value multiplicator: 28, 25, etc
+-- delete opened nodes (both)
+
+walk :: Int -> String -> Valves -> Int
+walk n start valves
+  | n == 0 = 0
+  | otherwise = n * rate + maximum [walk (pred n) x valves | x<-nextNodes]
+  where rate = valves M.! start ^._1
+        nextNodes = valves M.! start ^._2