Day 25git status!

README.md

@@ -36,4 +36,4 @@ Now located in this repository's wiki.
 | 22  |   23        |
 | 23  |   128       |
 | 24  | ~ 2         |
-| 25  |             |
+| 25  | ~ 1         |

app/Main.hs

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

src/Day25.hs

@@ -1,6 +1,37 @@
+{-# LANGUAGE ViewPatterns #-}
+
 module Day25 (main) where
 
+import Prelude hiding (null)
+import Data.Foldable (foldl')
+import Data.Set (Set, fromList, null, empty, insert, deleteFindMin, partition, union)
+
+type Point = (Int, Int, Int, Int)
+
+parse :: String -> Point
+parse str = read $ "(" ++ str ++ ")"
+
+manhattan :: Point -> Point -> Int
+manhattan (t1, x1, y1, z1) (t2, x2, y2, z2) = abs (t2 - t1) + abs (x2 - x1) + abs (y2 - y1) + abs (z2 - z1)
+
+-- constellation :: starting point -> points -> (points in same constellation, points not in same constellation)
+constellation :: Point -> Set Point -> (Set Point, Set Point)
+constellation p ps =
+    let (near, far)  = partition ((<= 3) . manhattan p) ps
+        (same, diff) = foldl' (\(n, f) p -> let (s, d) = constellation p f in (union n s, d)) (empty, far) near
+    in  (insert p $ union same near, diff)
+
+constellations :: Set Point -> [Set Point] -> [Set Point]
+constellations (null -> True) cs = cs
+constellations points cs =
+    let (p, ps) = deleteFindMin points
+        (same, diff) = constellation p ps
+    in  constellations diff (same:cs)
+
+part1 :: Set Point -> Int
+part1 points = length $ constellations points []
+
 main :: IO ()
 main = do
-    input <- readFile "input/25.txt"
+    input <- fromList . map parse . lines <$> readFile "input/25.txt"
-    print input
+    print $ part1 input