adventofcode/day02/src/main.rs

use std::error;
use std::fs::File;
use std::io::BufRead;
use std::io::BufReader;

#[derive(PartialEq)]
enum Values {
	Rock,
	Paper,
	Scissors,
}


impl Values {
	fn get_from_str(v: &str) -> Values {
		match v {
			"A" => Values::Rock,
			"B" => Values::Paper,
			"C" => Values::Scissors,
			_ => panic!("Unexpected value for Values")
		}
	}

	fn get_u32(&self) -> u32 {
		match self {
			Values::Rock => 1,
			Values::Paper => 2,
			Values::Scissors => 3,
		}
	}

	fn get_other(&self, play_result: &PlayResult) -> Values {
		match self {
			Values::Rock => {
				match play_result {
					PlayResult::Lose => Values::Scissors,
					PlayResult::Draw => Values::Rock,
					PlayResult::Win => Values::Paper
				}
			},
			Values::Paper => {
				match play_result {
					PlayResult::Lose => Values::Rock,
					PlayResult::Draw => Values::Paper,
					PlayResult::Win => Values::Scissors
				}
			},
			Values::Scissors => {
				match play_result {
					PlayResult::Lose => Values::Paper,
					PlayResult::Draw => Values::Scissors,
					PlayResult::Win => Values::Rock,
				}
			},
		}
	}
}

enum PlayResult {
	Lose,
	Draw,
	Win,
}

impl PlayResult {
	fn get_from_str(v: &str) -> PlayResult {
		match v {
			"X" => PlayResult::Lose,
			"Y" => PlayResult::Draw,
			"Z" => PlayResult::Win,
			_ => panic!("Unexpected value for PlayResult")
		}
	}

	fn get_u32(&self) -> u32 {
		match self {
			PlayResult::Lose => 0,
			PlayResult::Draw => 3,
			PlayResult::Win => 6
		}
	}
}

fn main() -> Result<(), Box<dyn error::Error>> {
	let f = File::open("input.txt")?;
	let reader = BufReader::new(f);

	let mut sum: u32 = 0;
	for line in reader.lines() {
		let line = line?;
		let split_result = line.split_whitespace().collect::<Vec<&str>>();
		let other = Values::get_from_str(split_result[0]);
		let play_result = PlayResult::get_from_str(split_result[1]);
		let my = other.get_other(&play_result);

		sum += my.get_u32();
		sum += play_result.get_u32();
	}

    println!("{}", sum);
    Ok(())
}