path: root/2023/rs/code/two/src/main.rs

use nom::{Parser, IResult};
use nom::character::complete::*;
use nom::bytes::complete::*;
use nom::sequence::*;
use nom::combinator::*;
use nom::number::complete as number;
use nom::multi::*;

struct Game {
  pub id: u32,
  pub rounds: Vec<Round>
}
#[derive(Default)]
struct Round {
  pub red: u8,
  pub green: u8,
  pub blue: u8
}

// feck, i think nom may have been a bit too much for this.

fn parse_game(i: &str) -> IResult<&str, Game> {
  separated_pair(
    preceded(
      tag("Game "),
      digit1.map(|s: &str| s.parse().unwrap())),
    tag(": "),
    separated_list1(
      tag("; "),
      fold_many0(
        terminated(
          separated_pair(
            digit1.map(|s: &str| s.parse().unwrap()),
            tag(" "),
            alpha1),
          opt(tag(", "))),
        || Round::default(),
        |mut r, (n, t)| match t {
          "red" => {r.red = n; r},
          "green" => {r.green = n; r},
          "blue" => {r.blue = n; r},
          _ => r
        }))).map(|(n, r)| Game{id: n, rounds: r}).parse(i)
}

static INPUT: &str = include_str!("input.txt");

fn main() {
  let valueified = INPUT.split("\n").filter(|s| !s.is_empty()).map(|g| parse_game(g).unwrap().1);

  let valid_id_sum = valueified.clone().filter(|g| !g.rounds.iter().any(|r| r.red > 12 || r.green > 13 || r.blue > 14)).map(|g| g.id).sum::<u32>();
  println!("Sum of valid IDs: {valid_id_sum}");

  let game_power_sum = valueified.map(|g| {
      let red = g.rounds.iter().map(|r| r.red).max().unwrap_or(0);
      let green = g.rounds.iter().map(|r| r.green).max().unwrap_or(0);
      let blue = g.rounds.iter().map(|r| r.blue).max().unwrap_or(0);
      red as u32 * green as u32 * blue as u32
    }).sum::<u32>();
  println!("Sum of game powers: {game_power_sum}");
}