Finish Day 2 - Part 1

.vscode/settings.json

@@ -11,6 +11,8 @@
     "factorise",
     "foldl",
     "HLINT",
+    "mempty",
+    "Prec",
     "unrecognised"
   ]
 }

src/advent_of_code/2023/2.hs

@@ -1,25 +1,78 @@
 -- https://adventofcode.com/2023/day/2
+{-# LANGUAGE OverloadedStrings #-}
 
--- imports
+import           Data.Bifunctor (Bifunctor (bimap, second))
+import           Data.Char      (isSpace)
+import           Data.List      (foldl', sort, (!!))
+import           Data.Text      (Text)
+import qualified Data.Text      as T
+import qualified Data.Text.IO   as T
 
 main :: IO ()
 main = do
-  entries <- lines <$> readFile "src/advent_of_code/2023/input2"
-  print "Advent of Code 2023 - Day 2"
-
-  print ("Part 1: " <> show (solveP1 entries))
-  print ("Part 2: " <> show (solveP2 entries))
+  entries <- T.lines <$> T.readFile "src/advent_of_code/2023/input2"
+  putStrLn "Advent of Code 2023 - Day 2"
+  -- print entries
+  putStrLn ("Part 1: " <> show (solveP1 entries))
+  -- putStrLn ("Part 2: " <> show (solveP2 entries))
 
 --
 -- Part 1
 --
 
-solveP1 :: [String] -> [String]
-solveP1 = id
+data Colour
+  = Red
+  | Green
+  | Blue
+  deriving (Show, Read, Ord, Eq)
+
+data Cube c n
+  = Cube c n
+  deriving (Show, Read, Ord, Eq)
+
+cubeLessThanLimit :: (Cube Colour Int, Cube Colour Int, Cube Colour Int) -> Cube Colour Int -> Bool
+cubeLessThanLimit (Cube Red n, _,   _) (Cube Red   v) = v <= n
+cubeLessThanLimit (_, Cube Green n, _) (Cube Green v) = v <= n
+cubeLessThanLimit (_, _,  Cube Blue n) (Cube Blue  v) = v <= n
+
+lessThanP1 :: Cube Colour Int -> Bool
+lessThanP1 = cubeLessThanLimit p1Limit
+
+p1Limit :: (Cube Colour Int, Cube Colour Int, Cube Colour Int)
+p1Limit =  (Cube Red     12, Cube Green   13, Cube Blue    14)
+
+solveP1 :: [Text] -> Int
+solveP1 = sum . map fst . filter snd . map (second (all (== True) . concatMap (map lessThanP1)) . parseInput)
 
 --
 -- Part 2
 --
 
-solveP2 :: [String] -> [String]
 solveP2 = id
+
+--
+-- Parsing
+--
+
+parseInput :: Text -> (Int, [[Cube Colour Int]])
+parseInput = bimap (read . T.unpack . T.drop 5) (map (map stringToCube . T.splitOn ", ") . T.splitOn "; " . T.drop 2) . T.breakOn ": "
+
+stringToCube :: Text -> Cube Colour Int
+stringToCube str = read $ "Cube " <> colour' <> " " <> n'
+  where
+    (n, colour) = second (T.drop 1) . T.break isSpace $ str
+    colour'     = T.unpack (T.toTitle colour)
+    n'          = T.unpack n
+
+--
+-- Examples
+--
+
+example1 :: [Text]
+example1 =
+  [ "Game 1: 3 blue, 4 red; 1 red, 2 green, 6 blue; 2 green"
+  , "Game 2: 1 blue, 2 green; 3 green, 4 blue, 1 red; 1 green, 1 blue"
+  , "Game 3: 8 green, 6 blue, 20 red; 5 blue, 4 red, 13 green; 5 green, 1 red"
+  , "Game 4: 1 green, 3 red, 6 blue; 3 green, 6 red; 3 green, 15 blue, 14 red"
+  , "Game 5: 6 red, 1 blue, 3 green; 2 blue, 1 red, 2 green"
+  ]