Initial day 22

2024/AOC2024/Day22.hs

@@ -21,9 +21,8 @@
 --     solution.  You can delete the type signatures completely and GHC
 --     will recommend what should go in place of the underscores.
 module AOC2024.Day22 (
--- day22a,
--- day22b
-
+  day22a,
+  day22b,
 )
 where
 
@@ -42,6 +41,7 @@ import qualified Data.OrdPSQ as PSQ
 import qualified Data.Sequence as Seq
 import qualified Data.Sequence.NonEmpty as NESeq
 import qualified Data.Set as S
+import Data.Bits
 import qualified Data.Set.NonEmpty as NES
 import qualified Data.Text as T
 import qualified Data.Vector as V
@@ -53,21 +53,67 @@ import qualified Text.Megaparsec.Char.Lexer as PP
 day22a :: _ :~> _
 day22a =
   MkSol
-    { sParse =
-        noFail $
-          lines
+    { sParse = parseMaybe' $ 
+          sepByLines pDecimal
+        -- noFail $
+        --   lines
     , sShow = show
     , sSolve =
         noFail $
-          id
+          sum . map ((!! 2000) . iterate step)
     }
 
+step :: Int -> Int
+step n = n'''
+  where
+    n' = prune $ (n*64) `xor` n
+    n'' = prune $ (n' `div` 32) `xor` n'
+    n''' = prune $ (n'' * 2048) `xor` n''
+    prune = (`mod` 16777216)
+
+-- -   Calculate the result of *multiplying the secret number by `64`*.
+--     Then, *mix* this result into the secret number. Finally, *prune* the
+--     secret number.
+-- -   Calculate the result of *dividing the secret number by `32`*. Round
+--     the result down to the nearest integer. Then, *mix* this result into
+--     the secret number. Finally, *prune* the secret number.
+-- -   Calculate the result of *multiplying the secret number by `2048`*.
+--     Then, *mix* this result into the secret number. Finally, *prune* the
+--     secret number.
+
+-- Each step of the above process involves *mixing* and *pruning*:
+
+-- -   To *mix* a value into the secret number, calculate the [bitwise
+--     XOR](https://en.wikipedia.org/wiki/Bitwise_operation#XOR){target="_blank"}
+--     of the given value and the secret number. Then, the secret number
+--     becomes the result of that operation. (If the secret number is `42`
+--     and you were to *mix* `15` into the secret number, the secret number
+--     would become `37`.)
+-- -   To *prune* the secret number, calculate the value of the secret
+--     number
+--     [modulo](https://en.wikipedia.org/wiki/Modulo){target="_blank"}
+--     `16777216`. Then, the secret number becomes the result of that
+--     operation. (If the secret number is `100000000` and you were to
+--     *prune* the secret number, the secret number would become
+--     `16113920`.)
+
 day22b :: _ :~> _
 day22b =
   MkSol
     { sParse = sParse day22a
     , sShow = show
     , sSolve =
-        noFail $
-          id
+        noFail $ \xs ->
+          let serieses = xs <&> \x ->
+                let ps = take 2000 $ map (`mod` 10) $ iterate step x 
+                    dPs = zipWith (\p0 p1 -> (p1, p1 - p0)) ps (drop 1 ps)
+                    windows = slidingWindows 4 dPs <&> \w -> (snd <$> w, fst $ last (toList w))
+                    seqMap = M.fromListWith (flip const) windows
+                in seqMap
+              bests = M.unionsWith (+) serieses
+           in snd $ maximumBy (comparing snd) (M.toList bests)
+              -- bests = M.unionsWith (<>) $ map (fmap (:[])) serieses
+           -- in maximumBy (comparing (sum . snd)) (M.toList bests)
     }
+  where
+    diffs xs = zipWith subtract xs (drop 1 xs)

test-data/2024/22a.txt

@@ -0,0 +1,5 @@
+1
+10
+100
+2024
+>>> 37327623

test-data/2024/22b.txt

@@ -0,0 +1,5 @@
+1
+2
+3
+2024
+>>> 23