adventofcode2022/day08/part2.rs

// Copyright 2022 Christian Ulrich
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.
//
// usage: ./part2 < input

pub mod common;

use common::{Direction, Forest};

fn main() -> Result<(), &'static str> {
    let forest = Forest::from_stdin()?;
    let (x_len, y_len) = forest.dimensions();
    let mut result = 0;
    for y in 0..y_len {
        for x in 0..x_len {
            let tree = forest.tree(x, y).unwrap();
            let mut scenic_score = 1;
            for direction in [
                Direction::North,
                Direction::East,
                Direction::South,
                Direction::West,
            ] {
                let mut viewing_distance = 0;
                for t in forest.view(x, y, direction).unwrap() {
                    match t {
                        _ if { t >= tree } => {
                            viewing_distance += 1;
                            break;
                        }
                        _ if { t < tree } => viewing_distance += 1,
                        _ => break,
                    }
                }
                scenic_score *= viewing_distance;
            }
            result = usize::max(result, scenic_score);
        }
    }
    println!("{result}");
    Ok(())
}