aoc2024/src/days/d1.rs

use crate::prelude::*;

pub type I = (B<Rev<u32>>, B<Rev<u32>>);
pub type O = u32;

fn _parse (data: &str) -> I {
    let (mut l, mut r) = (B::new(), B::new());
    data.lines().for_each(|line| {
        let mut iter = line.split_whitespace();

        let left = p!(n!(iter));
        let right = p!(n!(iter));
        l.push(Rev(left));
        r.push(Rev(right));
    });

    (l, r)
}

fn _silver ((left, right): I) -> O {
    left.into_iter_sorted().zip(right.into_iter_sorted()).fold(0, |acc, (l, r)| acc + l.0.abs_diff(r.0))
}

fn _gold ((left, right): I) -> O {
    let right = right.into_iter().map(|e| e.0).counts();

    left.into_iter().fold(0, |acc, cur| acc + cur.0 * *right.get(&cur.0).unwrap_or(&0) as u32)
}

#[cfg(test)]
mod test {
    use super::*;

    #[test]
    fn silver () {
        let data = _parse(inc!(1));
        let ans = _silver(data);

        assert_eq!(ans, 2196996)
    }

    #[test]
    fn gold () {
        let data = _parse(inc!(1));
        let ans = _gold(data);

        assert_eq!(ans, 23655822)
    }
}