From 1ad2d43ca1351bf55b7757400da1b3be0b2957f5 Mon Sep 17 00:00:00 2001
From: Neil Smith <NeilNjae@users.noreply.github.com>
Date: Tue, 3 Dec 2024 10:18:33 +0000
Subject: [PATCH] Done day 3

---
 advent03/Main.hs     | 69 ++++++++++++++++++++++++++++++++++++++++++++
 adventofcode24.cabal |  6 +++-
 2 files changed, 74 insertions(+), 1 deletion(-)
 create mode 100644 advent03/Main.hs

diff --git a/advent03/Main.hs b/advent03/Main.hs
new file mode 100644
index 0000000..59d64a3
--- /dev/null
+++ b/advent03/Main.hs
@@ -0,0 +1,69 @@
+-- Writeup at https://work.njae.me.uk/2024/12/03/advent-of-code-2024-day-3/
+
+import AoC
+import Data.List
+import Data.Text (Text)
+import qualified Data.Text.IO as TIO
+import Data.Attoparsec.Text hiding (take)
+
+
+data Term = Mul Int Int
+          | Junk Char
+          | DoTerm
+          | DontTerm
+          deriving (Eq, Show)
+
+main :: IO ()
+main = 
+  do  dataFileName <- getDataFileName
+      text <- TIO.readFile dataFileName
+      let program = successfulParse text
+      -- print program
+      -- print $ filter notJunk program
+      -- print $ enabledMuls program
+      print $ part1 program
+      print $ part2 program
+
+part1, part2 :: [Term] -> Int
+-- part1 program = sum $ fmap evalTerm program
+-- part2 program = sum $ fmap evalTerm $ enabledMuls program
+part1 = sum . fmap evalTerm
+part2 = sum . fmap evalTerm . enabledMuls 
+
+-- notJunk :: Term -> Bool
+-- notJunk (Mul _ _) = True
+-- notJunk DoTerm = True
+-- notJunk DontTerm = True
+-- notJunk _ = False
+
+evalTerm :: Term -> Int
+evalTerm (Mul a b) = a * b
+evalTerm _ = 0
+
+enabledMuls :: [Term] -> [Term]
+enabledMuls terms = snd $ foldl' go (True, []) terms
+  where go (True, ts) (Mul a b) = (True, Mul a b : ts)
+        go (_, ts) DontTerm = (False, ts)
+        go (_, ts) DoTerm = (True, ts)
+        go (c, ts) _ = (c, ts)
+
+-- Parse the input file
+
+junkP, doP, dontP, mulP :: Parser Term
+termsP :: Parser [Term]
+
+junkP = Junk <$> anyChar
+-- junksP = Junks <$> many1 anyChar
+doP = DoTerm <$ "do()"
+dontP = DontTerm <$ "don't()"
+mulP = Mul <$> ("mul(" *> decimal <* ",") <*> decimal <* ")"
+
+-- termsP = (++) <$> (many' junksP) <*> (mulP `sepBy` junksP)
+termsP = many' (choice [mulP, doP, dontP, junkP])
+
+successfulParse :: Text -> [Term]
+successfulParse input = 
+  case parseOnly termsP input of
+    Left  _err -> [] -- TIO.putStr $ T.pack $ parseErrorPretty err
+    Right matches -> matches
+
diff --git a/adventofcode24.cabal b/adventofcode24.cabal
index 7e4d98f..309f2e3 100644
--- a/adventofcode24.cabal
+++ b/adventofcode24.cabal
@@ -80,4 +80,8 @@ executable advent01
 executable advent02
   import: warnings, common-extensions, build-directives, common-modules
   main-is: advent02/Main.hs
-  
\ No newline at end of file
+
+executable advent03
+  import: warnings, common-extensions, build-directives, common-modules
+  main-is: advent03/Main.hs  
+  build-depends: attoparsec, text
-- 
2.34.1