2024 day 4

pub fn part_one(input: &str) -> Option<u32> {
    fn offsets(i: i32, j: i32, d: i32) -> Vec<(u32, i32, i32)> {
        vec![
            (0, i + d, j),
            (1, i + d, j + d),
            (2, i, j + d),
            (3, i - d, j + d),
            (4, i - d, j),
            (5, i - d, j - d),
            (6, i, j - d),
            (7, i + d, j - d),
        ]
    }

    let mut counts = HashMap::<(u32, i32, i32), u32>::new();
    input
        .split("\n")
        .enumerate()
        .map(|(i, l)| {
            l.chars()
                .enumerate()
                .map(move |(j, c)| match c {
                    'X' => offsets(i as i32, j as i32, 0),
                    'M' => offsets(i as i32, j as i32, 1),
                    'A' => offsets(i as i32, j as i32, 2),
                    'S' => offsets(i as i32, j as i32, 3),
                    _ => vec![],
                })
                .flatten()
        })
        .flatten()
        .for_each(|(d, i, j)| *counts.entry((d, i, j)).or_default() += 1);

    Some(counts.values().filter(|v| **v == 4).count() as u32)
}

pub fn part_two(input: &str) -> Option<u32> {
    fn offsets(i: i32, j: i32, d: i32) -> Vec<(u32, i32, i32)> {
        vec![
            (0, i + d, j + d),
            (1, i + d, j + d),
            (1, i - d, j + d),
            (2, i - d, j + d),
            (2, i - d, j - d),
            (3, i - d, j - d),
            (3, i + d, j - d),
            (0, i + d, j - d),
        ]
    }

    let mut counts = HashMap::<(u32, i32, i32), u32>::new();
    input
        .split("\n")
        .enumerate()
        .map(|(i, l)| {
            l.chars()
                .enumerate()
                .map(move |(j, c)| match c {
                    'M' => offsets(i as i32, j as i32, -1),
                    'A' => offsets(i as i32, j as i32, 0),
                    'S' => offsets(i as i32, j as i32, 1),
                    _ => vec![],
                })
                .flatten()
        })
        .flatten()
        .for_each(|(d, i, j)| *counts.entry((d, i, j)).or_default() += 1);

    // A will feature twice in votes, so need 6
    Some(counts.values().filter(|v| **v == 6).count() as u32)
}