From 275a3ec5d361381808378fede994b6e89db91fa0 Mon Sep 17 00:00:00 2001
From: Julien Dessaux
Date: Sat, 2 Dec 2023 16:04:44 +0100
Subject: 2023-02 in haskell

---
 2023/02-Cube_Conundrum/first.hs | 65 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 65 insertions(+)
 create mode 100644 2023/02-Cube_Conundrum/first.hs

(limited to '2023/02-Cube_Conundrum/first.hs')

diff --git a/2023/02-Cube_Conundrum/first.hs b/2023/02-Cube_Conundrum/first.hs
new file mode 100644
index 0000000..8b462d4
--- /dev/null
+++ b/2023/02-Cube_Conundrum/first.hs
@@ -0,0 +1,65 @@
+-- requires cabal install --lib megaparsec parser-combinators
+module Main (main) where
+
+import Control.Applicative.Permutations
+import Control.Monad (void, when)
+import Data.Char qualified as C
+import Data.List qualified as L
+import Data.Map qualified as M
+import Data.Maybe
+import Data.Set qualified as S
+import Data.Void (Void)
+import Text.Megaparsec
+import Text.Megaparsec.Char
+
+exampleExpectedOutput = 8
+
+data Draw = Draw Int Int Int deriving (Eq, Show)
+data Game = Game Int [Draw] deriving Show
+type Input = [Game]
+
+type Parser = Parsec Void String
+
+parseColor :: String -> Parser Int
+parseColor color = read <$> try (some digitChar <* char ' ' <* string color <* optional (string ", "))
+
+parseDraw :: Parser Draw
+parseDraw = do
+  (blue, green, red) <- runPermutation $
+    (,,) <$> toPermutationWithDefault 0 (parseColor "blue")
+         <*> toPermutationWithDefault 0 (parseColor "green")
+         <*> toPermutationWithDefault 0 (parseColor "red")
+  void . optional $ string "; "
+  return $ Draw blue green red
+
+parseGame :: Parser Game
+parseGame = do
+  id <- read <$> (string "Game " *> some digitChar <* optional (string ": "))
+  Game id <$> someTill parseDraw eol
+
+parseInput' :: Parser Input
+parseInput' = some parseGame <* 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'
+
+process :: Int -> Game -> Int
+process acc (Game id draws) | draws == draws' = acc + id
+                            | otherwise = acc
+  where
+    draws' = L.filter (\(Draw blue green red) -> blue <= 14 && green <= 13 && red <= 12) draws
+
+compute :: Input -> Int
+compute = L.foldl' process 0
+
+main :: IO ()
+main = do
+  example <- parseInput "example"
+  let exampleOutput = compute example
+  when  (exampleOutput /= exampleExpectedOutput)  (error $ "example failed: got " ++ show exampleOutput ++ " instead of " ++ show exampleExpectedOutput)
+  input <- parseInput "input"
+  print $ compute input
-- 
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