aoc2022/day_2b/src/main.rs

use std::fs;
use std::env;

use nom::IResult;
use nom::multi::separated_list0;
use nom::branch::alt;
use nom::bytes::complete::tag;
use nom::character::complete::i32;
use nom::character::complete::space1;
use nom::character::complete::space0;
use nom::combinator::value;
use nom::sequence::tuple;
use nom::sequence::preceded;
use nom::sequence::separated_pair;
use nom::sequence::terminated;

#[derive(Clone, Debug, PartialEq, Eq)]
enum Color {
    Red,
    Green,
    Blue,
}

#[derive(Clone, Debug, PartialEq, Eq)]
struct Draw {
    red_count: i32,
    green_count: i32,
    blue_count: i32,
}

#[derive(Clone, Debug, PartialEq, Eq)]
struct Game {
    id: i32,
    draws: Vec<Draw>,
}

fn parse_color(input: &str) -> IResult<&str, Color> {
    alt((
        value(Color::Red, tag("red")),
        value(Color::Green, tag("green")),
        value(Color::Blue, tag("blue")),
    ))(input)
}

fn parse_game_id(input: &str) -> IResult<&str, i32> {
    terminated(
        preceded(
            tuple((space0, tag("Game"),space1)),
            i32,
        ),
        space0,
    )(input)
}

fn parse_number_of_cubes(input: &str) -> IResult<&str, (i32, Color)> {
    preceded(
        space0,
        separated_pair(
            i32,
            space1,
            parse_color,
        )
    )(input)
}

fn parse_draw(input: &str) -> IResult<&str, Vec<(i32, Color)>> {
    separated_list0(
        tag(","),
        parse_number_of_cubes
    )(input)
}

fn parse_game_draws(input: &str) -> IResult<&str, Vec<Vec<(i32, Color)>>> {
    separated_list0(
        tag(";"),
        parse_draw
    )(input)
}

fn parse_input_line(input: &str) -> IResult<&str, (i32, Vec<Vec<(i32, Color)>>)> {
    separated_pair(
        parse_game_id,
        tag(":"),
        parse_game_draws,
    )(input)
}

fn create_game_from_data(data: (i32, Vec<Vec<(i32, Color)>>)) -> Game {
    let (id, draws_data) = data;
    let mut draws: Vec<Draw> = Vec::new();
    for draw_data in draws_data {
        let mut draw = Draw{
            red_count: 0,
            green_count: 0,
            blue_count: 0,
        };

        for color_count in draw_data {
            let (count, color) = color_count;
            match color {
                Color::Red => draw.red_count += count,
                Color::Green => draw.green_count += count,
                Color::Blue => draw.blue_count += count,
            }
        }
        draws.push(draw);
    }
    Game{
        id,
        draws,
    }
}

fn parse_game(input: &str) -> Result<Game, String> {
    match parse_input_line(input) {
        Ok((rest, data)) => if rest == "" {
            Ok(create_game_from_data(data))
        } else {
            Err(format!("Incomplete parse, remaining: {}", rest))
        },
        Err(error) => Err(error.to_string()),
    }
}

fn main() {
    let mut result = 0;

    let args: Vec<String> = env::args().collect();
    let file_path = &args[1];
    let input_data = fs::read_to_string(file_path).unwrap_or_else(
        |_|{panic!("Can't read file {}", file_path)});
    for line in input_data.lines() {
        let game = parse_game(line).unwrap_or_else(|e|panic!("Failed to parse line: {}", e));
        let mut max_red = 0;
        let mut max_green = 0;
        let mut max_blue = 0;
        for draw in &game.draws {
            if draw.red_count > max_red {
                max_red = draw.red_count;
            }
            if draw.green_count > max_green {
                max_green = draw.green_count;
            }
            if draw.blue_count > max_blue {
                max_blue = draw.blue_count;
            }
        }
        result += max_red * max_green * max_blue;
    }

    println!("{}", result);
}