Done day 7

diff --git a/advent06/Main.hs b/advent06/Main.hs
index ce9ac39bd3ce9a68b4e5b08d274d80f9417e450c..c4852f2b219085113f710e1d0a85fae4a33dc025 100644 (file)
--- a/advent06/Main.hs
+++ b/advent06/Main.hs
@@ -36,7 +36,7 @@ part1 grid guard = length $ nub $ walk grid guard
 
 part2 grid guard = length $ filter (isLoop guard []) modifiedGrids
   where modifiedGrids = [ grid // [ (new, True) ] 
-                        | new <- news -- range (bounds grid)
+                        | new <- news 
                         , new /= guard.pos
                         ]
         news = nub $ walk grid guard
@@ -58,13 +58,7 @@ step grid guard
   | otherwise = Just (guard.pos, guard { pos = ahead })
   where ahead = guard.pos ^+^ guard.dir
 
--- isLoop :: Guard -> [Guard] -> Grid -> Bool
--- isLoop guard trail grid
---   | isNothing stepped = False
---   | guard' `elem` trail = True
---   | otherwise = isLoop guard' (guard:trail) grid
---   where stepped = step grid guard
---         (_, guard') = fromJust stepped
+
 isLoop :: Guard -> [Guard] -> Grid -> Bool
 isLoop guard trail grid
   | isNothing stepped = False

diff --git a/advent06/MainPar.hs b/advent06/MainPar.hs
index a5bba98e74b887a99977d9b4835cdb4feebc3fc6..0eab5029680e127173bc9f2a19704b917600c714 100644 (file)
--- a/advent06/MainPar.hs
+++ b/advent06/MainPar.hs
@@ -36,7 +36,7 @@ part1 grid guard = length $ nub $ walk grid guard
 
 part2 grid guard = length $ filter id loopResults
   where modifiedGrids = [ grid // [ (new, True) ] 
-                        | new <- news -- range (bounds grid)
+                        | new <- news 
                         , new /= guard.pos
                         ]
         loopResults = parMap rpar (isLoop guard []) modifiedGrids
@@ -62,13 +62,6 @@ step grid guard
   | otherwise = Just (guard.pos, guard { pos = ahead })
   where ahead = guard.pos ^+^ guard.dir
 
--- isLoop :: Guard -> [Guard] -> Grid -> Bool
--- isLoop guard trail grid
---   | isNothing stepped = False
---   | guard' `elem` trail = True
---   | otherwise = isLoop guard' (guard:trail) grid
---   where stepped = step grid guard
---         (_, guard') = fromJust stepped
 isLoop :: Guard -> [Guard] -> Grid -> Bool
 isLoop guard trail grid
   | isNothing stepped = False

diff --git a/advent07/Main.hs b/advent07/Main.hs
new file mode 100644 (file)
index 0000000..687d19a
--- /dev/null
+++ b/advent07/Main.hs
@@ -0,0 +1,56 @@
+-- Writeup at https://work.njae.me.uk/2024/12/07/advent-of-code-2024-day-7/
+
+import AoC
+import Data.Text (Text)
+import qualified Data.Text.IO as TIO
+import Data.Attoparsec.Text 
+-- import Control.Applicative
+import Data.List
+
+type Calibration = (Int, [Int])
+
+main :: IO ()
+main = 
+  do  dataFileName <- getDataFileName
+      text <- TIO.readFile dataFileName
+      let calibrations = successfulParse text
+      -- print calibrations
+      print $ part1 calibrations
+      print $ part2 calibrations
+
+part1, part2 :: [Calibration] -> Int
+part1 = sum . (fmap fst) . filter isValid
+part2 = sum . (fmap fst) . filter isValidC
+
+isValid, isValidC :: Calibration -> Bool
+isValid  (target, factors) = target `elem` extend factors
+isValidC (target, factors) = target `elem` extendC factors
+
+extend, extendC :: [Int] -> [Int]
+extend  (x:xs) = foldl' extendOne  [x] xs
+extendC (x:xs) = foldl' extendOneC [x] xs
+
+extendOne, extendOneC :: [Int] -> Int -> [Int]
+extendOne  partials next = concatMap go partials
+  where go p = [p + next, p * next]
+
+extendOneC partials next = concatMap go partials
+  where go p = [ p + next
+               , p * next
+               , read (show p ++ show next)
+               ]
+
+-- parse the input file
+
+calibrationsP :: Parser [Calibration]
+calibrationP :: Parser Calibration
+
+calibrationsP = calibrationP `sepBy` endOfLine
+calibrationP = (,) <$> decimal <* ": " <*> (decimal `sepBy` " ")
+
+successfulParse :: Text -> [Calibration]
+successfulParse input = 
+  case parseOnly calibrationsP input of
+    Left  _err -> [] -- TIO.putStr $ T.pack $ parseErrorPretty err
+    Right caliibrations -> caliibrations
+

diff --git a/adventofcode24.cabal b/adventofcode24.cabal
index 903ceb9c9aa2c7ba0f25a62c7e47294f988866ec..87c1a445a6966ed193ab25b5d4b8699f53d04f6f 100644 (file)
--- a/adventofcode24.cabal
+++ b/adventofcode24.cabal
@@ -108,3 +108,9 @@ executable advent06par
   import: warnings, common-extensions, build-directives, common-modules
   main-is: advent06/MainPar.hs  
   build-depends: array, linear, parallel
+
+executable advent07
+  import: warnings, common-extensions, build-directives, common-modules
+  main-is: advent07/Main.hs  
+  build-depends: attoparsec, text
+  
\ No newline at end of file