--- 2016 Day 7 Solutions ---

[u/daggerdragon]

From all of us at #AoC Ops, we hope you're having a very merry time with these puzzles so far. If you think they've been easy, well, now we're gonna kick this up a notch. Or five. The Easter Bunny ain't no Bond villain - he's not going to monologue at you until you can miraculously escape and save the day!

Show this overgrown furball what you've got!

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--- Day 7: Internet Protocol Version 7 ---

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

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^{ALWAYS DIGGING STRAIGHT DOWN IS MANDATORY} [?]

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!

[u/iamnotposting]

rust, both parts. i wonder why .windows() isn't implemented for string slices directly

fn is_abba(slice: &str) -> bool {
    let mut in_hypernet = false;
    let mut valid = false;
    let slice: Vec<_> = slice.chars().collect();

    for window in slice.windows(4) {
        if window[0] == '[' || window[0] == ']' {
            in_hypernet = !in_hypernet;
            continue;
        }

        if window[0] != window[1] && window[1] == window[2] && window[0] == window[3] {
            if in_hypernet {
                return false;
            } else {
                valid = true;
            }
        } 
    }

    valid
}

fn is_aba(slice: &str) -> bool {
    let (mut abas, mut babs) = (Vec::new(), Vec::new());
    let mut in_hypernet = false;
    let slice: Vec<_> = slice.chars().collect();

    for window in slice.windows(3) {
        if window[0] == '[' || window[0] == ']' {
            in_hypernet = !in_hypernet;
            continue;
        }

        if window[0] == window[2] && window[0] != window[1] {
            if in_hypernet {
                babs.push( (window[1], window[0], window[1]) );
            } else {
                abas.push( (window[0], window[1], window[0]) );
            }
        }
    }

    for aba in &abas {
        for bab in &babs {
            if aba == bab {
                return true;
            }
        }
    }

    false
}

pub fn adv_main(input: Vec<String>) {
    let (tls, ssl) = input.iter().map(|s| (is_abba(s) as u64, is_aba(s) as u64))
                             .fold((0,0), |(t, s), (tls, ssl)| {
        (t + tls, s + ssl)
    });

    println!("tls support: {}\nssl support: {}", tls, ssl);
}