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Deebster

@ Deebster @programming.dev

Posts
58
Comments
1028
Joined
3 yr. ago

New account since lemmyrs.org went down, other @Deebsters are available.

  • 🐒 - 2024 DAY 22 SOLUTIONS - 🐒

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  • Have you tried gxhash or one of the other non-cryptographic hashers?

  • 💿 - 2024 DAY 9 SOLUTIONS -💿

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  • I just ran this on a laptop - it worked (part one only) but took 4h28m21s so Nushell is not a language for AoC (or I just coded it very poorly).

  • 🐒 - 2024 DAY 22 SOLUTIONS - 🐒

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  • Six minutes? 😅 I was feeling crappy about my 30 seconds (my naive big O cubed(?) logic means my code spends most of its time testing array equalities - 72 billion samples in the flamegraph!)

  • 🐒 - 2024 DAY 22 SOLUTIONS - 🐒

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  • How have I never noticed that scan() exists? Very handy.

    I liked the zipping of the offset prices, neater than my helper method.

  • 🐒 - 2024 DAY 22 SOLUTIONS - 🐒

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  • Rust

    Not too hard today, apart from yesterday's visit to a cocktail bar leaving me a little hazy in the mind.

     rust
        
use std::{fs, str::FromStr};

use color_eyre::eyre::{Report, Result};
use gxhash::{HashMap, HashMapExt};

const SECRETS_PER_DAY: usize = 2000;
const SEQ_LEN: usize = 4;

type Sequence = [i8; SEQ_LEN];

fn produce(n: usize) -> usize {
    let n = (n ^ (n * 64)) % 16777216;
    let n = (n ^ (n / 32)) % 16777216;
    (n ^ (n * 2048)) % 16777216
}

#[derive(Debug)]
struct Buyer {
    prices: [u8; SECRETS_PER_DAY + 1],
    changes: [i8; SECRETS_PER_DAY],
}

impl Buyer {
    fn price_at_seq(&self, seq: &Sequence) -> Option<u8> {
        self.changes
            .windows(SEQ_LEN)
            .position(|win| win == *seq)
            .and_then(|i| self.price_for_window(i))
    }

    fn price_for_window(&self, i: usize) -> Option<u8> {
        self.prices.get(i + SEQ_LEN).copied()
    }
}

struct BananaMarket {
    buyers: Vec<Buyer>,
}

impl FromStr for BananaMarket {
    type Err = Report;

    fn from_str(s: &str) -> Result<Self, Self::Err> {
        let buyer_seeds = s
            .lines()
            .map(|s| s.parse::<usize>())
            .collect::<Result<Vec<_>, _>>()?;

        let buyers = buyer_seeds
            .into_iter()
            .map(|seed| {
                let mut prices = [0; SECRETS_PER_DAY + 1];
                let mut changes = [0; SECRETS_PER_DAY];

                let mut secret = seed;
                let mut price = (seed % 10) as u8;
                prices[0] = price;
                for i in 0..SECRETS_PER_DAY {
                    let last_price = price;
                    secret = produce(secret);
                    price = (secret % 10) as u8;
                    prices[i + 1] = price;
                    changes[i] = price as i8 - last_price as i8;
                }
                Buyer { prices, changes }
            })
            .collect();
        Ok(Self { buyers })
    }
}

impl BananaMarket {
    fn sell_with_seq(&self, seq: &Sequence) -> usize {
        self.buyers
            .iter()
            .map(|b| b.price_at_seq(seq).unwrap_or(0) as usize)
            .sum()
    }

    fn maximise_bananas(&self) -> usize {
        let mut cache: HashMap<Sequence, usize> = HashMap::new();

        for seq in self
            .buyers
            .iter()
            .flat_map(|buyer| buyer.changes.windows(SEQ_LEN))
        {
            let seq = seq.try_into().unwrap();
            cache.entry(seq).or_insert_with(|| self.sell_with_seq(&seq));
        }

        cache.into_values().max().unwrap_or(0)
    }
}

fn part1(filepath: &str) -> Result<usize> {
    let input = fs::read_to_string(filepath)?
        .lines()
        .map(|s| s.parse::<usize>())
        .collect::<Result<Vec<_>, _>>()?;
    let res = input
        .into_iter()
        .map(|n| (0..SECRETS_PER_DAY).fold(n, |acc, _| produce(acc)))
        .sum();
    Ok(res)
}

fn part2(filepath: &str) -> Result<usize> {
    let input = fs::read_to_string(filepath)?;
    let market = BananaMarket::from_str(&input)?;
    Ok(market.maximise_bananas())
}

fn main() -> Result<()> {
    color_eyre::install()?;

    println!("Part 1: {}", part1("d22/input.txt")?);
    println!("Part 2: {}", part2("d22/input.txt")?);
    Ok(())
}

  • The Batcave is suspiciously guano-free. Alfred has some really thankless jobs.

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  • Wayne Industries Organic Fertilizer

  • 🏃‍♀️ - 2024 DAY 20 SOLUTIONS -🏃‍♀️

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  • I missed that line too:

    Because there is only a single path from the start to the end

    So I also did my pathfinding for every variation in the first part, but realised something must be wrong with my approach when I saw part 2.

  • [2024 day 8] Visualization! (see description for full input)

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  • That full version is extremely satisfying. I think it'd be even better if there were sound - maybe ascending notes in a scale like in some puzzle games.

  • Puppet is getting forked

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  • I like the take that they have in that thread: Perforce is forking Puppet into a non-Open Source version (but they're keeping the name).

  • Sweet Raspberry taste of success masks a missed opportunity

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  • But I said how they work, not, say, how to use a computer to get onto a website. I'm thinking of future generation's makers and tinkerers, which seemed to be the gist of the article you posted.

    The surface of computing is quite polished nowadays, but that's not entirely helpful when you can't access anything under the surface to learn what makes it tick.

  • Sweet Raspberry taste of success masks a missed opportunity

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  • I feel this article is looking at a bit of silver as if it's the lining and writing an article about the cloud.

    Definitely there's less knowledge about how computers work nowadays: e.g. universities now have to teach Computer Science students how file systems and directories work, because kids are used to saving everything in the default folder and just searching for what they want (and we're talking to those geeky enough to be doing CS).

    But there's more complexity now, and a lot of that stuff is just irrelevant busy work. I remember juggling IRQ lines when installing hardware but luckily that's auto-configured now. I used to create boot discs and eke out enough memory by skipping the better graphics, mouse driver, etc when not needed but did that teach me much?

    On the other hand, we used to have LAN parties as teenagers and would rebuild the networking stack for each game, including some performance tweaks (“Red Alert needs NetBIOS over IPX, right?” “Yeah, but disable the turbo encabulator”) and ¾ of us went on to do CS at uni. We certainly never thought of a web browser as “the internet” and we're confident to explore knowing we could fix what we broke (and did, often).

  • [2024 Day 16] Had to scrap my Dijkstra and implement bfs instead :/

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  • The main thing I remember about Dijkstra's algorithm was that at uni when we coded it up in the lab my version had a bug where a certain node was always 0, so I just left the mouse cursor on top of that mode when I demoed it - got full marks 🤓

  • [2024 day 4 p2] visualization

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  • I think just announce it's a thing and let people post as they will. I don't think a daily thread is necessary, for the reason you say but also that individual posts would get more attention - and extra attention is warranted since there's a lot of extra work that goes in to them.

  • [2024 day 4 p2] visualization

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  • Perhaps you could run an “advent of vis” where on the first of Jan we post visualisations of our solutions for day 1, etc.

  • [2024 day 6] Visualization (see description for viz of full input)

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  • Maybe you're already editing it in, but there's no description in your post.

  • Raft, by Stephen Baxter

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  • That's a six book series, if I remember rightly. I love Pratchett's stuff (Men at Arms is next on my Discworld reread) but I was thinking of his solo stuff. Normally I just start at the first published if I think I'll enjoy the whole lot.

  • Raft, by Stephen Baxter

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  • I haven't read anything by him, where is a good place to start? Here?

  • [Solved]PC froze, now what?

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  • That kills Xorg, right? Does it work on Wayland, or is there something similar?

  • 💿 - 2024 DAY 9 SOLUTIONS -💿

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  • Haha, thanks but we both know they're #1 by a country mile. I think my phone's now downclocking as it's burning up and still hasn't spat out an answer after two hours, so I technically haven't completed it yet!

    Edit: Calling it for now, I might figure out later why it's so slow (there's some easy but minor gains to be made but I'm guessing there's some O(awful) going on that the input's blown up)