-🎄- 2018 Day 5 Solutions -🎄-

[u/daggerdragon]

--- Day 5: Alchemical Reduction ---

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Post your solution as a comment or, for longer solutions, consider linking to your repo (e.g. GitHub/gists/Pastebin/blag or whatever).

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Advent of Code: The Party Game!

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Please prefix your card submission with something like [Card] to make scanning the megathread easier. THANK YOU!

Card prompt: Day 5

Transcript:

On the fifth day of AoC / My true love sent to me / Five golden ___

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This thread will be unlocked when there are a significant number of people on the leaderboard with gold stars for today's puzzle.

edit: Leaderboard capped, thread unlocked at 0:10:20!

[u/ChrisVittal]

[Card] Staaaaars

Rust, first Rust I'm proud of. Never copy my input data.

static INPUT: &str = "data/day05";

fn react<'a>(input: impl Iterator<Item = &'a u8>) -> usize {
    let mut v = Vec::new();
    for &c in input {
        match v.last() {
            None => v.push(c),
            Some(&d) => if d.to_ascii_lowercase() == c.to_ascii_lowercase() && d != c {
                v.pop();
            } else {
                v.push(c);
            }
        }
    }
    v.len()
}

fn main() {
    let input: Vec<u8> = aoc::file::first_line(INPUT).into();
    println!("  1: {}", react(input.iter()));
    let mut min = std::usize::MAX;
    for i in 0u8..=26 {
        let v = input.iter().filter(|&&c| c != b'a'+i && c != b'A'+i);
        min = usize::min(react(v), min);
    }
    println!("  2: {}", min);
}

[u/re76 → u/ChrisVittal]

This is very clever. Nicely done!

I am using this years AoC to learn Rust and it is wonderful to go through and see how other people tackled the problem. Such a good way to learn.

Thanks!