2022/src/bin/day01.rs

use aoc_2022::file_to_lines;

use color_eyre::eyre::Result;
use tracing::*;
use tracing_subscriber::EnvFilter;

fn n_biggest(n: usize, input: &[i32]) -> i32 {
    let mut calories: Vec<i32> = Vec::new();

    let last_elf = input.iter().fold(0, |a, &x| {
        if x == -1 {
            calories.push(a);
            0
        } else {
            a + x
        }
    });
    calories.push(last_elf);

    calories.sort();
    calories.iter().rev().take(n).sum()
}

fn part_1(input: &[i32]) -> i32 {
    n_biggest(1_usize, input)
}

fn part_2(input: &[i32]) -> i32 {
    n_biggest(3_usize, input)
}

fn parse_input(pathname: &str) -> Vec<i32> {
    file_to_lines(pathname)
        .iter()
        .map(|s| if s.is_empty() { -1 } else { s.parse().unwrap() })
        .collect()
}

fn main() -> Result<()> {
    tracing_subscriber::fmt()
        .with_env_filter(EnvFilter::from_default_env())
        .with_target(false)
        .with_file(true)
        .with_line_number(true)
        .without_time()
        .compact()
        .init();
    color_eyre::install()?;

    let input = parse_input("inputs/day01.txt");

    info!("Part 1: {}", part_1(&input));
    info!("Part 2: {}", part_2(&input));

    Ok(())
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn test_part_1() {
        let sample = parse_input("samples/day01.txt");
        assert_eq!(part_1(&sample), 24000);
    }

    #[test]
    fn test_part_2() {
        let sample = parse_input("samples/day01.txt");
        assert_eq!(part_2(&sample), 45000);
    }
}