Day 23 - part 1.

app/Main.hs

@@ -30,4 +30,4 @@ import qualified Day24
 import qualified Day25
 
 main :: IO ()
-main = Day22.main
+main = Day23.main

src/Day23.hs

@@ -1,6 +1,35 @@
 module Day23 (main) where
 
+data Bot = Bot Position Radius deriving (Eq)
+type Position = (Int, Int, Int)
+type Radius = Int
+
+instance Ord Bot where
+    Bot _ rad1 <= Bot _ rad2 = rad1 <= rad2
+
+parse :: String -> Bot
+parse str =
+    let pos = takeWhile (/= '>') . drop 5 $ str
+        rad = drop 2 . last . words $ str
+    in  Bot (read $ "(" ++ pos ++ ")") (read rad)
+
+manhattan :: Position -> Position -> Int
+manhattan (x1, y1, z1) (x2, y2, z2) = abs (x1 - x2) + abs (y1 - y2) + abs (z1 - z2)
+
+-- botInRange b1 b2 = is b2 within the range of b1?
+botInRange :: Bot -> Bot -> Bool
+botInRange (Bot pos1 radius) (Bot pos2 _) = manhattan pos1 pos2 <= radius
+
+-- inRange pos bot = is pos within the range of bot?
+inRange :: Bot -> Position -> Bool
+inRange (Bot bPos radius) pos = manhattan bPos pos <= radius
+
+part1 :: [Bot] -> Int
+part1 bots =
+    let maxBot = maximum bots
+    in  length $ filter (botInRange maxBot) bots
+
 main :: IO ()
 main = do
-    input <- readFile "input/23.txt"
-    print input
+    bots <- map parse . lines <$> readFile "input/23.txt"
+    print $ part1 bots