Created
December 16, 2023 02:59
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Day 14 AOC 2023
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| {-# LANGUAGE OverloadedStrings #-} | |
| module DayFourteen where | |
| import qualified Data.Text as T | |
| import Data.Ratio ((%)) | |
| import qualified Data.List as L | |
| import qualified Text.Read as TR | |
| import Debug.Trace (traceShowId, traceShow) | |
| import qualified Data.Maybe as M | |
| import qualified Data.Map as DM | |
| import qualified Data.Set as S | |
| import qualified Data.List.Split as DLS | |
| import qualified Data.Range as R | |
| import qualified Data.Sequence as DS | |
| import Data.Sequence as DS (index, (!?)) | |
| import Data.Sequence ((<|), (|>)) | |
| import Data.Range ((+=+), (+=*)) | |
| import Safe (atDef, atMay, minimumMay, headMay, headDef) | |
| import Data.Foldable (toList) | |
| testMirrorInput :: [T.Text] | |
| testMirrorInput = ["O....#....", | |
| "O.OO#....#", | |
| ".....##...", | |
| "OO.#O....O", | |
| ".O.....O#.", | |
| "O.#..O.#.#", | |
| "..O..#O..O", | |
| ".......O..", | |
| "#....###..", | |
| "#OO..#...."] | |
| testMirror = parseMirror testMirrorInput | |
| parseMirror lines = DS.fromList (map DS.fromList lists) | |
| where lists = map ((map parseMirrorCell) . T.unpack) lines | |
| data Cell = Round | Cubic | Empty deriving (Eq, Ord) | |
| data Direction = North | South | East | West deriving (Eq, Ord) | |
| instance Show Cell where | |
| show Round = "O" | |
| show Cubic = "#" | |
| show _ = "." | |
| parseMirrorCell 'O' = Round | |
| parseMirrorCell '#' = Cubic | |
| parseMirrorCell _ = Empty | |
| swapCells mirror (sr,sc) (tr, tc) = (putBack . copyOver) mirror | |
| where sourceItem = (mirror `index` sr) `index` sc | |
| destItem = (mirror `index` tr) `index` tc | |
| copyOver = DS.adjust (DS.update tc sourceItem) tr | |
| putBack = DS.adjust (DS.update sc destItem) sr | |
| swapInDirection direction mirror@(Mirror grid positions) (r,c) = Mirror (swapCells grid (r,c) newPosition) (updatePositionsSet positions) | |
| where newPosition = (moveTowards direction (r,c)) | |
| updatePositionsSet = (S.delete (r, c)) . (S.insert newPosition) | |
| moveTowards North (r,c) = (r-1,c) | |
| moveTowards South (r,c) = (r+1,c) | |
| moveTowards East (r,c) = (r,c+1) | |
| moveTowards West (r,c) = (r,c-1) | |
| canRollInDirection grid direction (r,c) = M.fromMaybe False maybeAnswer | |
| where (targetRow, targetCol) = moveTowards direction (r,c) | |
| hereIsRound = ((grid `index` r) `index` c) == Round | |
| maybeAnswer = do | |
| destinationRow <- grid !? targetRow | |
| destinationCell <- destinationRow !? targetCol | |
| Just (destinationCell == Empty && hereIsRound) | |
| allIndices mirror = do | |
| r <- 0 `enumFromTo` (length mirror - 1) | |
| c <- 0 `enumFromTo` (length (mirror `index` 0) - 1) | |
| [(r,c)] | |
| data Mirror = Mirror (DS.Seq (DS.Seq Cell)) (S.Set (Int, Int)) deriving (Ord, Eq, Show) | |
| buildMirror grid = Mirror grid $ S.fromList $ filter isRound (allIndices grid) | |
| where isRound (r,c) = ((grid `index` r) `index` c) == Round | |
| iterateRolling :: Mirror -> Direction -> Mirror | |
| iterateRolling mirror@(Mirror grid roundPositions) direction = foldl (swapInDirection direction) mirror toMove | |
| where toMove = S.filter (canRollInDirection grid direction) $ roundPositions | |
| rollUntilComplete direction mirror | |
| | iterated == mirror = mirror | |
| | otherwise = rollUntilComplete direction iterated | |
| where iterated = iterateRolling mirror direction | |
| cycleMirror = (rollUntilComplete East) . (rollUntilComplete South) . (rollUntilComplete West) . (rollUntilComplete North) -- . traceShowId | |
| firstDuplicatedItem seenSoFar (head:rest) | |
| | head `elem` seenSoFar = head | |
| | otherwise = firstDuplicatedItem (S.insert head seenSoFar) rest | |
| firstDuplicatedMirror seed = firstDuplicatedItem S.empty $ iterate cycleMirror seed | |
| cycleDescription seed = take 2 $ L.elemIndices fd $ iterate cycleMirror seed | |
| where fd = firstDuplicatedMirror seed | |
| scoreMirror mirror = sum $ map scoreRow zipped | |
| where zipped = zip (map toList (toList $ DS.reverse mirror)) (enumFrom 1) | |
| scoreRow (items, rank) = rank * (length (filter (== Round) items)) | |
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