Advent of Code 2021 - Day 5: Hydrothermal Venture

hydrothermal_venture.rs

struct Point {
    x: i16,
    y: i16,
}

struct Line {
    start: Point,
    end: Point,
}

fn find_points(lines: &[Line]) -> usize {
    let mut map = [[0; 1000]; 1000];

    lines.iter().filter(|l| l.start.x == l.end.x).for_each(|l| {
        for y in i16::min(l.start.y, l.end.y)..=i16::max(l.start.y, l.end.y) {
            map[l.start.x as usize][y as usize] += 1;
        }
    });

    lines.iter().filter(|l| l.start.y == l.end.y).for_each(|l| {
        for x in i16::min(l.start.x, l.end.x)..=i16::max(l.start.x, l.end.x) {
            map[x as usize][l.start.y as usize] += 1;
        }
    });

    map.iter()
            .flat_map(|c| c.iter())
            .filter(|&&p| p > 1)
            .count()
}

fn find_points2(lines: &[Line]) -> usize {
    let mut map = [[0; 1000]; 1000];

    lines.iter().for_each(|l| {
        let mut x = l.start.x;
        let mut y = l.start.y;

        let x_step = l.end.x.cmp(&l.start.x) as i16;
        let y_step = l.end.y.cmp(&l.start.y) as i16;

        loop {
            map[x as usize][y as usize] += 1;

            if x == l.end.x && y == l.end.y {
                break;
            }

            x += x_step;
            y += y_step;
        }
    });

    map.iter()
            .flat_map(|c| c.iter())
            .filter(|&&p| p > 1)
            .count()
}