Done day 19, but not sure why attoparsec isn't working

[advent-of-code-20.git] / advent19 / src / advent19.hs

diff --git a/advent19/src/advent19.hs b/advent19/src/advent19.hs
new file mode 100644 (file)
index 0000000..01e872d
--- /dev/null
+++ b/advent19/src/advent19.hs
@@ -0,0 +1,87 @@
+-- import Debug.Trace
+
+import Text.ParserCombinators.ReadP
+-- import Text.ParserCombinators.ReadP ((+++))
+import Data.Char (isDigit, isAlpha)
+
+import qualified Data.IntMap.Strict as M
+import Data.IntMap.Strict ((!))
+
+import Data.Functor (void)
+import Data.Either
+
+
+data Rule = Letter Char 
+          -- | Then2 Rule Rule
+          -- | Then3 Rule Rule Rule
+          | Then [Rule]
+          | Or Rule Rule
+          | See Int
+          deriving (Show, Eq)
+
+type RuleSet = M.IntMap Rule
+
+
+main :: IO ()
+main = 
+  do  text <- readFile "data/advent19.txt"
+      -- print text
+      let (rules, messages) = parse inputP text
+      print $ part1 rules messages
+      print $ part2 rules messages
+      -- print $ part2 text
+
+setup fname = 
+  do text <- readFile fname
+     let (rules, messages) = parse inputP text
+     let newRules = parse rulesP "8: 42 | 42 8\n11: 42 31 | 42 11 31"
+     let updatedRules = M.union newRules rules
+     let myParser = makeParser updatedRules (See 0)
+     return (myParser, updatedRules, messages)
+
+
+part1 = countMatches
+
+part2 rules messages = countMatches updatedRules messages
+  where newRules = parse rulesP "8: 42 | 42 8\n11: 42 31 | 42 11 31"
+        updatedRules = M.union newRules rules
+
+countMatches rules messages 
+  = length $ filter ((== "") . snd) results
+  where myParser = makeParser rules (See 0)
+        results = concatMap (readP_to_S myParser) messages
+
+
+parse :: ReadP a -> String -> a
+parse parser str = fst $ head $ filter ((== "") . snd) $ readP_to_S parser str
+
+
+-- Generate the rules
+
+makeParser :: RuleSet -> Rule -> ReadP ()
+makeParser m (Letter c) = void $ char c
+makeParser m (Then rs) = mapM_ (makeParser m) rs
+makeParser m (Or a b) = (makeParser m a) +++ (makeParser m b)
+makeParser m (See i) = makeParser m (m!i)
+
+
+-- Parse the input
+
+rulesP = M.fromList <$> ruleP `sepBy` endOfLine
+ruleP = (,) <$> decimal <* (string ": ") <*> ruleBodyP
+ruleBodyP = choice [letterRuleP, orRuleP, thenRuleP, seeRuleP]
+
+letterRuleP = Letter <$> between (string "\"") (string "\"") get
+orRuleP = Or <$> thenRuleP <* (string " | ") <*> thenRuleP
+thenRuleP = Then <$> seeRuleP `sepBy` (string " ")
+seeRuleP = See <$> decimal
+
+
+inputP = (,) <$> rulesP <* blankLines <*> messagesP
+
+messagesP = (munch1 isAlpha) `sepBy` endOfLine
+
+blankLines = skipMany1 endOfLine
+
+decimal = read <$> many1 (satisfy isDigit)
+endOfLine = char '\n'