08.rs

#![feature(test)]

use aoc::{grid::Direction, iter_ext::IterExt};

type Input = Vec<Vec<u8>>;

struct CoordIterator {
    x: usize,
    y: usize,
    width: usize,
    height: usize,
    direction: Direction,
}

impl Iterator for CoordIterator {
    type Item = (usize, usize);

    fn next(&mut self) -> Option<Self::Item> {
        (self.x, self.y) = self
            .direction
            .step(self.x, self.y, self.width, self.height)?;
        Some((self.x, self.y))
    }
}

fn setup(input: &str) -> Input {
    input
        .trim()
        .lines()
        .map(|line| line.bytes().map(|x| x - b'0').collect())
        .collect()
}

fn part1(grid: &Input) -> usize {
    let (height, width) = (grid.len(), grid[0].len());

    (0..height)
        .flat_map(|y| {
            (0..width).filter(move |&x| {
                Direction::iter().any(|direction| {
                    CoordIterator {
                        x,
                        y,
                        width,
                        height,
                        direction,
                    }
                    .all(|(j, i)| grid[y][x] > grid[i][j])
                })
            })
        })
        .count()
}

fn part2(grid: &Input) -> usize {
    let (height, width) = (grid.len(), grid[0].len());

    (0..height)
        .flat_map(|y| {
            (0..width).map(move |x| {
                Direction::iter()
                    .map(|direction| {
                        CoordIterator {
                            x,
                            y,
                            width,
                            height,
                            direction,
                        }
                        .take_while_inclusive(|&(j, i)| grid[y][x] > grid[i][j])
                        .count()
                    })
                    .product::<usize>()
            })
        })
        .max()
        .unwrap()
}

aoc::main!(2022, 8, ex: 1);