this post was submitted on 25 Dec 2024
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Advent Of Code

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An unofficial home for the advent of code community on programming.dev!

Advent of Code is an annual Advent calendar of small programming puzzles for a variety of skill sets and skill levels that can be solved in any programming language you like.

AoC 2024

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console.log('Hello World')

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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

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Rust

Nice ending for this year. Lock and key arrays are just added together and all elements must be <= 5. Merry Christmas!

Solution

fn flatten_block(block: Vec<Vec<bool>>) -> [u8; 5] {
    let mut flat = [0; 5];
    for row in &block[1..=5] {
        for x in 0..5 {
            if row[x] {
                flat[x] += 1;
            }
        }
    }
    flat
}

fn parse(input: &str) -> (Vec<[u8; 5]>, Vec<[u8; 5]>) {
    let mut locks = Vec::new();
    let mut keys = Vec::new();
    for block_s in input.split("\n\n") {
        let block: Vec<Vec<bool>> = block_s
            .lines()
            .map(|l| l.bytes().map(|b| b == b'#').collect::<Vec<bool>>())
            .collect();
        assert_eq!(block.len(), 7);
        // Lock
        if block[0].iter().all(|e| *e) {
            locks.push(flatten_block(block));
        } else {
            keys.push(flatten_block(block));
        }
    }
    (locks, keys)
}

fn part1(input: String) {
    let (locks, keys) = parse(&input);
    let mut count = 0u32;
    for l in locks {
        for k in &keys {
            if l.iter().zip(k).map(|(li, ki)| li + ki).all(|sum| sum <= 5) {
                count += 1;
            }
        }
    }
    println!("{count}");
}

fn part2(_input: String) {
    println!("โญ");
}

util::aoc_main!();

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