aoc2016/src/days/d15.rs

#![allow(unused_imports)]
use crate::prelude::*;

pub type I = Vec<(usize, usize)>;
pub type O = usize;

fn _parse (data: &str) -> I {
    data.lines()
        .map(|e| e.trim().trim_matches('.')
            .split_once(" has ")
            .map(|(_, r)|
                r.split_once(" positions; at time=0, it is at position ")
                    .map(|(n, p)| (n.parse().unwrap(), p.parse().unwrap()))
            )
            .flatten()
            .unwrap()
        )
        .collect()
}

fn _solve (data: &I) -> O {
    let d = |time, (size, position)| (time + position) % size == 0;
    (0..).into_iter().find(|t| data.iter().enumerate().all(|(i, &df)| d(t + i + 1, df))).unwrap()
}

fn _silver (data: I) -> O {
    _solve(&data)
}

fn _gold (mut data: I) -> O {
    data.push((11, 0));
    _solve(&data)
}

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

    fn read () -> I {
        let data = inc!(15);
        _parse(data)
    }

    #[test]
    fn silver () {
        let data = read();
        let ans = _silver(data);

        assert_eq!(ans, 122318)
    }

    #[test]
    fn gold () {
        let data = read();
        let ans = _gold(data);

        assert_eq!(ans, 3208583)
    }
}