Day 4: Restroom Redoubt

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FAQ

  • VegOwOtenks@lemmy.worldEnglish
    2·
    11 hours ago

    Haskell

    I solved part two interactively, I’m not very happy about it

    Reveal Code 
    import Control.Arrow
import Data.Bifunctor hiding (first, second)
import Control.Monad

import qualified Data.List as List
import qualified Data.Set as Set
import qualified Data.Map as Map
import qualified Data.Maybe as Maybe

parse :: String -> [((Int, Int), (Int, Int))]
parse = map (break (== ' ') >>> second (drop 1) >>> join bimap (drop 2) >>> join bimap (break (== ',')) >>> join bimap (second (drop 1)) >>> join bimap (join bimap read)) . filter (/= "") . lines

moveRobot ((px, py), (vx, vy)) t = (px + t * vx, py + t * vy)

constrainCoordinates (mx, my) (px, py) = (px `mod` mx, py `mod` my)

coordinateConstraints = (101, 103)

robotQuadrant (mx, my) (px, py)
        | px > middleX && py < middleY = Just 1 -- upper right
        | px > middleX && py > middleY = Just 2 -- lower right
        | px < middleX && py > middleY = Just 3 -- lower left
        | px < middleX && py < middleY = Just 4 -- upper left
        | otherwise = Nothing
        where
                middleX = (mx `div` 2)
                middleY = (my `div` 2)

countQuadrants (q1, q2, q3, q4) 1 = (succ q1, q2, q3, q4)
countQuadrants (q1, q2, q3, q4) 2 = (q1, succ q2, q3, q4)
countQuadrants (q1, q2, q3, q4) 3 = (q1, q2, succ q3, q4)
countQuadrants (q1, q2, q3, q4) 4 = (q1, q2, q3, succ q4)

part1 = map (flip moveRobot 100 >>> constrainCoordinates coordinateConstraints)
        >>> map (robotQuadrant coordinateConstraints)
        >>> Maybe.catMaybes
        >>> foldl (countQuadrants) (0, 0, 0, 0)
        >>> \ (a, b, c, d) -> a * b * c * d

showMaybe (Just i) = head . show $ i
showMaybe Nothing  = ' '

buildRobotString robotMap = [ [ showMaybe (robotMap Map.!? (x, y))  | x <- [0..fst coordinateConstraints] ] | y <- [0..snd coordinateConstraints]]

part2 rs t = map (flip moveRobot t >>> constrainCoordinates coordinateConstraints)
        >>> flip zip (repeat 1)
        >>> Map.fromListWith (+)
        >>> buildRobotString
        $ rs

showConstellation (i, s) = do
        putStrLn (replicate 49 '#' ++ show i ++ replicate 49 '#')
        putStrLn $ s

main = do
        f <- getContents
        let i = parse f
        print $ part1 i

        let constellations = map (id &&& (part2 i >>> List.intercalate "\n")) . filter ((== 86) . (`mod` 103)) $ [0..1000000]
        mapM_ showConstellation constellations
        print 7502