AdventOfCode/rust/src/day02/part_1.rs

use crate::CubeCounts;

pub(crate) fn part_1(input: &'static str) -> usize {
    let id_sum = input
        .lines()
        .enumerate()
        .filter_map(|(game_id, line)| {
            let game_start_index = line.find(":").expect("Every line should have a ': '") + 2;

            let game = &line[game_start_index..];

            let groups = game.split("; ");

            let game_counts = groups
                .map(|group| {
                    let color_counts = group.split(", ");

                    let group_counts = color_counts.map(|color_count| {
                        let (count, color) = color_count
                            .split_once(' ')
                            .expect("Every color count should have one space");

                        let count = count
                            .parse()
                            .expect("Every color count should be a valid number");

                        match color {
                            "red" => CubeCounts::red(count),
                            "green" => CubeCounts::green(count),
                            "blue" => CubeCounts::blue(count),
                            _ => unreachable!(),
                        }
                    });
                    group_counts.sum::<CubeCounts>()
                })
                .reduce(|acc, cube_count| CubeCounts {
                    red: u16::max(acc.red, cube_count.red),
                    green: u16::max(acc.green, cube_count.green),
                    blue: u16::max(acc.blue, cube_count.blue),
                })
                .expect("At least one group should exist in each game");
            if game_counts.red <= 12 && game_counts.green <= 13 && game_counts.blue <= 14 {
                Some(game_id + 1)
            } else {
                None
            }
        })
        .sum();
    id_sum
}

#[cfg(test)]
mod tests {
    const SAMPLE_INPUT: &str = include_str!("sample_input.txt");

    #[test]
    fn test_with_sample_solution() {
        assert_eq!(super::part_1(SAMPLE_INPUT), 8)
    }

    #[test]
    fn test_with_solution() {
        assert_eq!(super::part_1(crate::INPUT), 2449);
    }
}