AOC 2023 Day 11 - all about transposition

day_eleven_2023.hs

{-# LANGUAGE OverloadedStrings #-}
module DayEleven where

import qualified Data.Text as T
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.Set as S
import Safe (atDef, atMay, minimumMay, headMay)

-- SETUP
data Tile = Empty | Galaxy deriving (Eq, Show, Ord)
type Universe = [[Tile]]

parseTile '#' = Galaxy
parseTile _ = Empty

parseUniverse = map ((map parseTile) . T.unpack)



buildIdxGrid universe = (map (\idx -> (map (\ri -> (idx, ri)) row)) colIdxs)
  where colIdxs = 0 `enumFromTo` (height - 1)
        row = 0 `enumFromTo` (width - 1)
        height = length universe
        width = length $ head universe

galaxyIndices universe = filter hasGalaxy allIndices
  where allIndices = concat $ buildIdxGrid  universe
        hasGalaxy (r,c) = ((universe !! r) !! c) == Galaxy

manhattan (a,b) (c,d) = (abs (a-c)) + (abs (b-d))

universeTestCase :: [T.Text]
universeTestCase = ["...#......",
                    ".......#..",
                    "#.........",
                    "..........",
                    "......#...",
                    ".#........",
                    ".........#",
                    "..........",
                    ".......#..",
                    "#...#....."]

-- Part 1
expandRow row
  | all (== Empty) row = [row, row]
  | otherwise = [row]

expandUniverseVertically universe = concatMap expandRow universe

fullyExpand = expandUniverseVertically . L.transpose . expandUniverseVertically . L.transpose

partOne universe = do
  first <- gi
  second <- gi
  if (first >= second) then [] else [manhattan first second]
  where gi = galaxyIndices universe

-- Part 2
rowCost expansionFactor row
  | all (== Empty) row = expansionFactor
  | otherwise = 1

inclusiveRange a b = (min a b) `enumFromTo` (max a b)

verticalTravelCost expansionFactor universe startRow endRow = sum $ map (rowCost expansionFactor) rows
  where rows = map (universe !!) (inclusiveRange startRow endRow)

horizontalTravelCost expansionFactor universe startCol endCol = verticalTravelCost expansionFactor (L.transpose universe) startCol endCol

partTwoDistance expansionFactor universe start@(sr,sc) end@(er,ec) = (verticalTravelCost expansionFactor universe sr er) + (horizontalTravelCost expansionFactor universe sc ec) - 2


partTwo expansionFactor universe = do
  first <- gi
  second <- gi
  if (first >= second) then [] else [dist first second]
  where gi = galaxyIndices universe
        dist = partTwoDistance expansionFactor universe