Hi guys.

I just did day1 of 2024 (I know, I'm late) this might be a dumb question but I reallydont understand why we should sort the two lists before substracting? I created some test cases with 10-20 items and calculated them manually, if you don't sort the list and just add all list1 items and substract from the sum of list2, you get the same answer. But it doesn't work with the large input file.

Let's say list1 has elements (a,b,c,d) and list2 has (e,f,g,h).

(a-e)+(b-f)+(c-g)+(d-h) = a-e+b-f+c-g+d-h = (a+b+c+d)-(e+f+g+h)

So the sorting shouldn't matter. Right? But it does. Am I too bad at basic math?

hi I know this is a year old, but I solved it and used a custom implementation of binary search to solve this.
interestingly enough, in python at least, it is almost as performant as the quadratic equation for solving this lol (43.7 microseconds vs 64.9 microseconds) but now that I realized it is a simple parabola, you can just get the maximum after getting the minimum time and practically matches the quadratic equation performance. lol I know the math is faster as search space grows but I still think its interesting how performant this was.

TLDR: I'm so data structures and programming pilled that I forgot basic algebra.

::: spoiler code

 py

    
from os.path import dirname,realpath,join

def profiler(method):
    from time import perf_counter_ns
    def wrapper_method(*args: any, **kwargs: any) -> any:
        start_time = perf_counter_ns()
        ret = method(*args, **kwargs)
        stop_time = perf_counter_ns() - start_time
        time_len = min(9, ((len(str(stop_time))-1)//3)
  

I'm looking for something like this (these are not correct, just an example for what I'm looking for):

• 2021 - day 1: Dijkstra Algorithm
• 2021 - day 2: Dynamic Programming
• 2021 - day 3: Time efficiency, Hash tables
• etc

If there is no such thing, does anyone have a (fairly) complete (github) repository of python implementations from which I can build such a list myself? I would make all the puzzles myself, but I'm not that fast, I'm currently still on day 15 of 2024.

Visualizations are hard, and take time, so here is a thread to highlight the visualizations that we have found/created.

Please feel free to post your visualisations!

Those of you running behind, keep at it, but this is the leaderboard as it stands at the end of 2024.

Happy new year!

Hello,

I am trying to solve the day 7 using Rust and this is what I came up with so far:

 undefined

    
use std::fs;

fn calculate(answer: &i32, numbers: &mut Vec<i32>) -> bool {
    if numbers.len() >= 2 {
    let tmp1 = numbers[0];
    let tmp2 = numbers[1];
    numbers.remove(0);
    numbers.remove(0);

    numbers.insert(0, tmp1 * tmp2);

    if calculate(answer, numbers) == true {
        return true;
    } else {
        numbers.remove(0);
        numbers.insert(0, tmp1 + tmp2);
        if calculate(answer, numbers) == true {
        return true;
        } else {
        return false;
        }
    }
    } else {
    if *answer == numbers[0] {
        println!("> {} true", numbers[0]);
        return true;
    } else {
        println!("> {} false", numbers[0]);
        return false;
    }
    }
}

fn main() {
    let contents = fs::read_to_string("sample.txt")
        .expect("Should have been able to read the file");

    for line in contents.lines() {
    let tmp = line.split(":").collect::<Vec<&str>>();
    let answer = tmp[0].to_string().parse::<i32>().unwrap();
    
  

A lot lower success rate than I suspected, I guess a lot of the scoreboard times were probably legit?

Now that Advent of Code 2024 has concluded, I wanted to get people's opinion on what puzzles they especially liked looking back. This could be because of the puzzle mechanics, the description, because you are especially proud of your solution that day, or for any other reason.

Feel free to answer even if you only saw part of the puzzles.

My picks would be:

• 14 (Restroom Redoubt, robots moving into christmas tree shape). Even though it caught me off-guard in the moment, I did like that part 2 had this very imprecise requirement for once. Definitely made for varied, creative solutions.
• 15 (Warehouse Woes, robots pushing boxes) The second part was a fairly big complexity spike with just a minor change in the tasks. Basically a form of simulation where the hard part is finding a good data representation for the setup. I liked this one because debugging was such a visual process for me, by printing the grids.
• 17 (Chronospatial Computer, running a machine code) For me the first reall

Well, that was a month. Congrats everyone who has reached the end, and thanks to everyone who has contributed solutions and advice.

Sometime in January I will create a megathread for visualizations. If anyone has any other ideas, happy to hear them, otherwise, take a well earned 11 month rest until next year :D

Here's a writeup of my experience this year! It's been a lot of fun, especially hanging out with people here and on Mastodon. Thanks everyone, and Eric in particular!

Day 25: Code Chronicle

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)
• You can send code in code blocks by using three backticks, the code, and then three backticks or use something such as https://topaz.github.io/paste/ if you prefer sending it through a URL

FAQ

• What is this?: Here is a post with a large amount of details: https://programming.dev/post/6637268
• Where do I participate?: https://adventofcode.com/
• Is there a leaderboard for the community?: We have a programming.dev leaderboard with the info on how to join in this post: https://programming.dev/post/6631465

I am wondering if manual inspection is the way to go for pt2? Seems almost achievable with some formatting. Anyone been down this road?

Day 24: Crossed Wires

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)
• You can send code in code blocks by using three backticks, the code, and then three backticks or use something such as https://topaz.github.io/paste/ if you prefer sending it through a URL

FAQ

• What is this?: Here is a post with a large amount of details: https://programming.dev/post/6637268
• Where do I participate?: https://adventofcode.com/
• Is there a leaderboard for the community?: We have a programming.dev leaderboard with the info on how to join in this post: https://programming.dev/post/6631465

Day 23: LAN Party

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)
• You can send code in code blocks by using three backticks, the code, and then three backticks or use something such as https://topaz.github.io/paste/ if you prefer sending it through a URL

FAQ

• What is this?: Here is a post with a large amount of details: https://programming.dev/post/6637268
• Where do I participate?: https://adventofcode.com/
• Is there a leaderboard for the community?: We have a programming.dev leaderboard with the info on how to join in this post: https://programming.dev/post/6631465

Day 22: Monkey Market

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)
• You can send code in code blocks by using three backticks, the code, and then three backticks or use something such as https://topaz.github.io/paste/ if you prefer sending it through a URL

FAQ

• What is this?: Here is a post with a large amount of details: https://programming.dev/post/6637268
• Where do I participate?: https://adventofcode.com/
• Is there a leaderboard for the community?: We have a programming.dev leaderboard with the info on how to join in this post: https://programming.dev/post/6631465

Day 21: Keypad Conundrum

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)
• You can send code in code blocks by using three backticks, the code, and then three backticks or use something such as https://topaz.github.io/paste/ if you prefer sending it through a URL

FAQ

• What is this?: Here is a post with a large amount of details: https://programming.dev/post/6637268
• Where do I participate?: https://adventofcode.com/
• Is there a leaderboard for the community?: We have a programming.dev leaderboard with the info on how to join in this post: https://programming.dev/post/6631465