4 files changed, 188 insertions, 0 deletions
diff --git a/2023/20-Pulse_Propagation/example b/2023/20-Pulse_Propagation/example
new file mode 100644
index 0000000..2dc1bab
--- /dev/null
+++ b/2023/20-Pulse_Propagation/example
@@ -0,0 +1,5 @@
+broadcaster -> a, b, c
+%a -> b
+%b -> c
+%c -> inv
+&inv -> a
diff --git a/2023/20-Pulse_Propagation/example2 b/2023/20-Pulse_Propagation/example2
new file mode 100644
index 0000000..2738ceb
--- /dev/null
+++ b/2023/20-Pulse_Propagation/example2
@@ -0,0 +1,5 @@
+broadcaster -> a
+%a -> inv, con
+&inv -> b
+%b -> con
+&con -> output
diff --git a/2023/20-Pulse_Propagation/first.hs b/2023/20-Pulse_Propagation/first.hs
new file mode 100644
index 0000000..c43e332
--- /dev/null
+++ b/2023/20-Pulse_Propagation/first.hs
@@ -0,0 +1,120 @@
+-- requires cabal install --lib megaparsec parser-combinators heap vector
+module Main (main) where
+
+import           Control.Applicative.Permutations
+import           Control.Monad                    (void, when)
+import qualified Data.Char                        as C
+import           Data.Either
+import           Data.Functor
+import qualified Data.Heap                        as H
+import qualified Data.List                        as L
+import qualified Data.Map                         as M
+import           Data.Maybe
+import qualified Data.Set                         as S
+import qualified Data.Vector                      as V
+import qualified Data.Vector.Unboxed              as VU
+import           Data.Void                        (Void)
+import           Text.Megaparsec
+import           Text.Megaparsec.Char
+
+import           Debug.Trace
+
+exampleExpectedOutput = 32000000
+example2ExpectedOutput = 11687500
+data Pulse = Low | High deriving (Eq, Show)
+data Module = Normal | FlipFlop Bool | Conjunction (M.Map String Pulse) | Broadcaster deriving (Eq, Show)
+data Configuration = Configuration Module String [String] deriving (Eq, Show)
+type Conf = (Module, [String])
+type Input = M.Map String Conf
+
+type Parser = Parsec Void String
+
+parseModule :: Parser Module
+parseModule = char '%' $> FlipFlop False
+          <|> char '&' $> Conjunction M.empty
+          <|> lookAhead (string "broadcaster") $> Broadcaster
+          <|> lookAhead letterChar $> Normal
+
+parseLabel :: Parser String
+parseLabel = some letterChar
+
+parseConfiguration :: Parser Configuration
+parseConfiguration = Configuration <$> parseModule
+                                   <*> parseLabel <* string " -> "
+                                   <*> some (parseLabel <* optional (string ", "))
+
+parseInput' :: Parser Input
+parseInput' = M.fromList . map (\(Configuration m s l) -> (s, (m, l))) <$> some (parseConfiguration <* eol) <* eof
+
+parseInput :: String -> IO Input
+parseInput filename = do
+  input <- readFile filename
+  case runParser parseInput' filename input of
+    Left bundle  -> error $ errorBundlePretty bundle
+    Right input' -> return input'
+
+compute :: Input -> Int
+compute input = let (x, y) = computeX 1000 (0, 0) $ initConjuctions input in x * y
+  where
+    computeX :: Int -> (Int, Int) -> Input -> (Int, Int)
+    computeX 0 n _ = n
+    computeX i n input = let (n', input') = compute' (1, 0) [("button", Low, "broadcaster")] input
+                         in computeX (i-1) (scoreAdd n n') input'
+    compute' :: (Int, Int) -> [(String, Pulse, String)] -> Input -> ((Int, Int), Input)
+    compute' n [] input = (n, input)
+    compute' n signals input | length stepAll == 0 = (n, input)
+                             | otherwise = compute' (scoreAdd n $ score stepAll) stepAll alterAll
+      where
+        alterAll :: Input
+        alterAll = L.foldl' alterOne input signals
+        alterOne :: Input -> (String, Pulse, String) -> Input
+        alterOne acc (prev, p, me) = alter p prev me acc (M.lookup me input)
+        alter :: Pulse -> String -> String -> Input -> Maybe Conf -> Input
+        alter _    _    _  input (Just (Normal, _))         = input
+        alter High _    _  input (Just (FlipFlop _, _))     = input
+        alter Low  _    me input (Just (FlipFlop False, l)) = M.insert me (FlipFlop True, l) input
+        alter Low  _    me input (Just (FlipFlop True, l))  = M.insert me (FlipFlop False, l) input
+        alter p    prev me input (Just (Conjunction m, l))  = M.insert me (Conjunction $ M.insert prev p m, l) input
+        alter p    _    _  input (Just (Broadcaster, l))    = input
+        alter _    _    _  input Nothing                    = input
+        score :: [(String, Pulse, String)] -> (Int, Int)
+        score = L.foldl' scoreOne (0, 0)
+        scoreOne :: (Int, Int) -> (String, Pulse, String) -> (Int, Int)
+        scoreOne (x, y) (_, Low, _)  = (x + 1, y)
+        scoreOne (x, y) (_, High, _) = (x, y + 1)
+        stepAll :: [(String, Pulse, String)]
+        stepAll = L.foldl' stepOne [] signals
+        stepOne :: [(String, Pulse, String)] -> (String, Pulse, String) -> [(String, Pulse, String)]
+        stepOne acc (prev, p, s) = step p prev s acc (M.lookup s input)
+        step :: Pulse -> String -> String -> [(String, Pulse, String)] -> Maybe Conf -> [(String, Pulse, String)]
+        step _    _    _  acc (Just (Normal, _))         = acc
+        step High _    _  acc (Just (FlipFlop _, _))     = acc
+        step Low  _    me acc (Just (FlipFlop False, l)) = acc ++ map (set me High) l
+        step Low  _    me acc (Just (FlipFlop True, l))  = acc ++ map (set me Low) l
+        step p    prev me acc (Just (Conjunction m, l))  = let p2 = if length (M.filter (\x -> x == High) $ M.insert prev p m) == length m then Low else High
+                                                           in acc ++ map (set me p2) l
+        step p    _    me acc (Just (Broadcaster, l))    = acc ++ map (set me p) l
+        step _    _    _  acc Nothing                    = acc
+    initConjuctions :: Input -> Input
+    initConjuctions input = let r = M.foldrWithKey initConf input input in r
+    initConf :: String -> Conf -> Input -> Input
+    initConf c (_, l) input = L.foldl' initOne input l
+      where
+        initOne :: Input -> String -> Input
+        initOne input s = case M.lookup s input of
+          Just (Conjunction m, l) -> M.insert s (Conjunction (M.insert c Low m), l) input
+          _ -> input
+    scoreAdd (x, y) (x', y') = (x + x', y + y')
+    set :: String -> Pulse -> String -> (String, Pulse, String)
+    set me p s = (me, p, s)
+
+main :: IO ()
+main = do
+  example <- parseInput "example"
+  let exampleOutput = compute example
+  when  (exampleOutput /= exampleExpectedOutput)  (error $ "example failed: got " ++ show exampleOutput ++ " instead of " ++ show exampleExpectedOutput)
+  example2 <- parseInput "example2"
+  let example2Output = compute example2
+  when  (example2Output /= example2ExpectedOutput)  (error $ "example2 failed: got " ++ show example2Output ++ " instead of " ++ show example2ExpectedOutput)
+  input <- parseInput "input"
+  print $ compute input
diff --git a/2023/20-Pulse_Propagation/input b/2023/20-Pulse_Propagation/input
new file mode 100644
index 0000000..32d7954
--- /dev/null
+++ b/2023/20-Pulse_Propagation/input
@@ -0,0 +1,58 @@
+%bz -> rb, mf
+%tn -> kb, md
+broadcaster -> nr, tn, bx, nx
+%jp -> ps
+&kc -> rx
+%dh -> kb, lt
+%lt -> cq, kb
+%ps -> mf, fh
+%sr -> nh, jh
+%jg -> tv
+%bx -> fd, jg
+%kg -> fd, lg
+%fh -> dp
+%hv -> mf, bz
+%mj -> zv
+%rz -> gq, mf
+%tc -> td
+%bl -> fd
+%lg -> fd, qj
+%gq -> hc, mf
+%kh -> ck
+%td -> kb, bm
+%cq -> kx, kb
+%zv -> tk
+&nh -> kh, zv, tk, mj, nx, qm, ph
+%tk -> mc
+%nr -> jp, mf
+%bt -> rz
+%dj -> nh, qm
+%qt -> gb, fd
+%rb -> mf
+&ph -> kc
+%dp -> bt, mf
+&kb -> hn, md, tc, tn, mr
+%gb -> fd, qs
+&vn -> kc
+%rt -> kg, fd
+%ck -> nh, sr
+%qx -> rt, fd
+%jh -> pt, nh
+%mr -> rs
+%nx -> nh, dj
+%qm -> mj
+&fd -> bx, kt, jg
+%rs -> kb, dh
+%bm -> kb, mr
+%tv -> qx, fd
+%pt -> nh
+%qj -> qt, fd
+%kx -> kb
+%qs -> bl, fd
+%md -> hh
+%hh -> tc, kb
+%mc -> kh, nh
+%hc -> hv
+&kt -> kc
+&mf -> fh, vn, bt, hc, nr, jp
+&hn -> kc