aoc 2022 day08

day08.rs

use core::num;

fn parse(input: &str) -> Vec<Vec<u32>> {
    let mut grid = vec![];
    for line in input.split("\n") {
        let mut row = vec![];
        for c in line.chars() {
            let i = c.to_digit(10).unwrap();
            row.push(i);
        }
        grid.push(row);
    }
    grid
}

fn is_visible(grid: &Vec<Vec<u32>>, x: usize, y: usize) -> bool {
    let tree_height = grid[y][x];

    // from the left
    let mut from_left = true;
    for i in 0..x {
        if grid[y][i] >= tree_height {
            from_left = false;
            break;
        }
    }

    // from the right
    let mut from_right = true;
    for i in x + 1..grid[y].len() {
        if grid[y][i] >= tree_height {
            from_right = false;
            break;
        }
    }

    // from the top
    let mut from_top = true;
    for i in 0..y {
        if grid[i][x] >= tree_height {
            from_top = false;
            break;
        }
    }

    // from the bottom
    let mut from_bottom = true;
    for i in y + 1..grid.len() {
        if grid[i][x] >= tree_height {
            from_bottom = false;
            break;
        }
    }

    from_left || from_right || from_top || from_bottom
}

fn scenic_score(grid: &Vec<Vec<u32>>, x: usize, y: usize) -> i32 {
    let tree_height = grid[y][x];

    let mut left_score = 0;
    for i in (0..x).rev() {
        left_score += 1;
        if grid[y][i] >= tree_height {
            break;
        }
    }

    let mut right_score = 0;
    for i in x + 1..grid[y].len() {
        right_score += 1;
        if grid[y][i] >= tree_height {
            break;
        }
    }

    let mut up_score = 0;
    for i in (0..y).rev() {
        up_score += 1;
        if grid[i][x] >= tree_height {
            break;
        }
    }

    let mut down_score = 0;
    for i in y + 1..grid.len() {
        down_score += 1;
        if grid[i][x] >= tree_height {
            break;
        }
    }

    left_score * right_score * up_score * down_score
}

fn main() {
    let grid = parse(include_str!("day08_input.txt"));
    // could just brute force check each tree.
    let mut num_visible = 0;
    let mut max_score = 0;
    for y in 0..grid.len() {
        for x in 0..grid[y].len() {
            if is_visible(&grid, x, y) {
                num_visible += 1;
            }
            let score = scenic_score(&grid, x, y);
            if score > max_score {
                max_score = score;
            }
        }
    }
    eprintln!("num visible: {num_visible}");
    eprintln!("max score: {max_score}");
}