Day 3: Lobby

Megathread guidelines

  • Keep top level comments as only solutions, if you want to say something other than a solution put it in a new post. (replies to comments can be whatever)
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FAQ

  • VegOwOtenks@lemmy.worldEnglish
    2·
    1 month ago

    Futhark

    I am on my way to re-do all previous days in Futhark and complete the Rest of AoC, hopefully.

    def hole: u8 = 0
def zipIndices 'a (xs: []a): [](i64, a) = zip (indices xs) xs
def foldMin (xs: []u8): (i64, u8) = 
  let indexedXs = tail (zipIndices xs) in
  let start = (0, head xs) in
  foldl (\ (ci, cv) (ni, nv) -> if nv > cv then (ni, nv) else (ci, cv)) start indexedXs

def slice 'a (xs: []a) (start: i64) (end: i64) = drop start (take end xs)

def pickBattery (bank: []u8) (reserved: i64): (i64, u8) = 
  let batteries = slice bank 0 (length bank - reserved) in
  foldMin batteries

def pickNBatteries (n: i8) (banks: []u8): u64 =
  let (_, result) =
    loop (batteries, sum) = (banks, 0)
    for i in reverse (0...n-1)
    do
      let (offset, battery) = pickBattery batteries (i64.i8 i) in
      (drop (offset + 1) batteries, sum * 10 + u64.u8 battery)
  in result

def part1 (banks: [][]u8): u64 = reduce (+) 0 (map (pickNBatteries 2) banks)

def part2 (banks: [][]u8): u64 = reduce (+) 0 (map (pickNBatteries 12) banks)

def main (banks: [][]u8) = (part1 banks, part2 banks)
    Script to Generate input for Futhark 
    {-# OPTIONS_GHC -Wall #-}
{-# LANGUAGE OverloadedStrings #-}
import qualified Data.Text.IO as TextIO
import Control.Monad ((<$!>))
import qualified Data.Array.Unboxed as Array
import qualified Data.Text as Text
import qualified Data.Char as Char
import Data.Array.Unboxed (UArray)
import qualified Data.List as List
import qualified Data.ByteString as ByteString
import Data.Word (byteSwap64, Word64)
import GHC.ByteOrder (ByteOrder(..), targetByteOrder)
import qualified Data.Bits as Bits

parse :: Text.Text -> UArray (Int, Int) Int
parse t = let
    banks = init $ Text.lines t
    bankSize = maybe 0 pred $ Text.findIndex (== '\n') t
    bankCount = Text.count "\n" t - 2
  in Array.listArray ((0, 0), (bankCount, bankSize)) $ List.concatMap (fmap Char.digitToInt . Text.unpack) banks

rowsOf :: UArray (Int, Int) Int -> Int
rowsOf = fst . snd . Array.bounds

colsOf :: UArray (Int, Int) Int -> Int
colsOf = snd . snd . Array.bounds

byteStringLeWord64 :: Word64 -> ByteString.ByteString
byteStringLeWord64 word = let
    leWord = case targetByteOrder of
      BigEndian -> byteSwap64 word
      LittleEndian -> word
  in ByteString.pack . map (fromIntegral . (leWord `Bits.shiftR`)) $ [0,8..56]

main :: IO ()
main = do
  batteryBanks <- parse <$!> TextIO.getContents
  putChar 'b'
  ByteString.putStr (ByteString.singleton 2) -- version
  ByteString.putStr (ByteString.singleton 2) -- dimensions
  TextIO.putStr "  u8" -- type
  ByteString.putStr (byteStringLeWord64 . fromIntegral . succ . rowsOf $ batteryBanks) -- outer dim
  ByteString.putStr (byteStringLeWord64 . fromIntegral . succ . colsOf $ batteryBanks) -- inner dim
  ByteString.putStr . ByteString.pack . fmap fromIntegral . Array.elems $ batteryBanks -- elements