43 lines
1.4 KiB
Haskell
43 lines
1.4 KiB
Haskell
import Data.List.Split (splitOn)
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import Data.List (elemIndex, sortOn, groupBy)
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import Data.Monoid ((<>))
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import Data.Function (on)
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import Data.Vector.Class
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import Data.Vector.V3
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data Particle = Particle {
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position :: Vector3,
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velocity :: Vector3,
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acceleration :: Vector3
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}
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instance Ord Vector3 where
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Vector3 x1 y1 z1 `compare` Vector3 x2 y2 z2 = compare x1 x2 <> compare y1 y2 <> compare z1 z2
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norm :: Vector3 -> Double
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norm (Vector3 x y z) = abs x + abs y + abs z
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updateParticle :: Double -> Particle -> Particle
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updateParticle t (Particle p v a) =
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Particle (p + t *| v + (t * (t + 1) / 2) *| a) (v + t *| a) a
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stepParticles :: [Particle] -> [Particle]
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stepParticles particles =
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concat . filter ((== 1) . length) . groupBy ((==) `on` position) . sortOn position . map (updateParticle 1) $ particles
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parseProperty :: String -> Vector3
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parseProperty str =
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let x : y : z : [] = map read . splitOn "," . drop 3 . init $ str
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in Vector3 x y z
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parseLine :: String -> Particle
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parseLine str =
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let p : v : a : [] = map parseProperty . splitOn ", " $ str
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in Particle p v a
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main :: IO ()
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main = do
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particles <- map parseLine . lines <$> readFile "20.txt"
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let distances = map (norm . position . updateParticle 400) particles
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print $ elemIndex (minimum distances) distances
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print $ length $ iterate stepParticles particles !! 40 |