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Day Nine 2023
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| {-# LANGUAGE OverloadedStrings #-} | |
| module DayNine where | |
| import qualified Data.Text as T | |
| import qualified Text.Read as TR | |
| import qualified Data.List as L | |
| import Safe (atMay, tailMay) | |
| import qualified Data.Maybe as M | |
| import Lib (operateOnFile) | |
| derivative = L.unfoldr calculateDifference | |
| where calculateDifference items = do | |
| firstElement <- items `atMay` 0 | |
| secondElement <- items `atMay` 1 | |
| tail <- tailMay items | |
| return (secondElement - firstElement, tail) | |
| allDerivatives :: [Int] -> [[Int]] | |
| allDerivatives f = takeWhile notDone $ iterate derivative f | |
| where notDone = any (/= 0) | |
| seeds = (map head) . allDerivatives | |
| integrate seed [] = [] | |
| integrate seed derivative@(h:t) = (seed) : (integrate (seed + h) t) | |
| generify f = foldr integrate (repeat 0) (seeds f) | |
| extrapolatedValue f = (generify f) !! (length f) | |
| testInput :: [T.Text] | |
| testInput = ["0 3 6 9 12 15", | |
| "1 3 6 10 15 21", | |
| "10 13 16 21 30 45"] | |
| partOne lines = sum $ map extrapolatedValue $ parsed | |
| where parsed :: [[Int]] | |
| parsed = map (M.catMaybes . (map readString) . (T.split (== ' '))) lines | |
| readString = TR.readMaybe . T.unpack | |
| partTwo lines = sum $ map (extrapolatedValue . reverse) $ parsed | |
| where parsed :: [[Int]] | |
| parsed = map (M.catMaybes . (map readString) . (T.split (== ' '))) lines | |
| readString = TR.readMaybe . T.unpack |
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