feat(day5): part 1 babyyyy

day5/Main.hs

@@ -0,0 +1,44 @@
+module Main where
+
+import System.Environment (getArgs)
+import Data.Maybe (mapMaybe)
+
+import Text.Parsec (parse, Parsec, endBy, sepBy1, char, newline, many)
+import Text.ParserCombinators.Parsec.Number (decimal)
+
+type PageOrdering = (Int, Int)
+type PagesUpdate = [Int]
+
+printInfo :: Parsec String () ([PageOrdering], [PagesUpdate])
+printInfo = (,) <$> orderings <*> (newline *> pagesUpdates) <* many (char '\n')
+    where
+        pagesUpdates :: Parsec String () [PagesUpdate]
+        pagesUpdates = endBy (sepBy1 decimal $ char ',') newline
+
+        orderings :: Parsec String () [PageOrdering]
+        orderings = endBy ((,) <$> decimal <*> (char '|' *> decimal)) $ char '\n'
+
+allDependencies :: [a] -> [(a, a)]
+allDependencies (h:tl) = map (flip (,) h) tl ++ allDependencies tl
+allDependencies [] = []
+
+middleElement :: [a] -> Maybe a
+middleElement [] = Nothing
+middleElement [a] = Just a
+middleElement (_:h':tl) = case reverse (h':tl) of
+    (_:middle) -> middleElement middle
+    [] -> Nothing
+
+part1 :: FilePath -> IO Int
+part1 fp = do
+    content <- readFile fp
+    (requiredOrderings, pagesUpdates) <- either (fail . show) return $ parse printInfo fp content
+    let wellOrdered = filter (all (`notElem` requiredOrderings) . allDependencies) pagesUpdates
+    return $ sum $ mapMaybe middleElement wellOrdered
+
+main :: IO ()
+main = do
+    args <- getArgs
+    (fp:_) <- return args
+    resPart1 <- part1 fp
+    putStrLn $ "Solution (Part 1) : " ++ show resPart1

day5/test_input

@@ -0,0 +1,28 @@
+47|53
+97|13
+97|61
+97|47
+75|29
+61|13
+75|53
+29|13
+97|29
+53|29
+61|53
+97|53
+61|29
+47|13
+75|47
+97|75
+47|61
+75|61
+47|29
+75|13
+53|13
+
+75,47,61,53,29
+97,61,53,29,13
+75,29,13
+75,97,47,61,53
+61,13,29
+97,13,75,29,47

kalmennAOC2024.cabal

@@ -50,3 +50,13 @@ executable day4
                       parsec ^>= 3.1.17.0
     hs-source-dirs:   day4
     default-language: Haskell2010
+
+executable day5
+    import:           warnings
+    main-is:          Main.hs
+    build-depends:
+                      base ^>=4.18.2.1,
+                      parsec ^>= 3.1.17.0,
+                      parsec-numbers ^>= 0.1.0
+    hs-source-dirs:   day5
+    default-language: Haskell2010