aoc22/src/day2.rs

#[derive(PartialEq, Debug)]
pub enum Choice {
    Rock,
    Paper,
    Scissors,
}

impl Choice {
    pub fn score(&self) -> u32 {
        match self {
            Choice::Rock => 1,
            Choice::Paper => 2,
            Choice::Scissors => 3,
        }
    }
}

#[derive(Debug)]
pub struct Round {
    opponent: Choice,
    own: Choice,
}

pub enum RoundResult {
    Win,
    Draw,
    Loss,
}

impl Round {
    pub fn result(&self) -> RoundResult {
        let win = match self.own {
            Choice::Rock => Choice::Scissors,
            Choice::Paper => Choice::Rock,
            Choice::Scissors => Choice::Paper,
        };

        if self.opponent == win {
            RoundResult::Win
        } else if self.opponent == self.own {
            RoundResult::Draw
        } else {
            RoundResult::Loss
        }
    }

    pub fn score(&self) -> u32 {
        let choice_score = self.own.score();
        let result_score = match self.result() {
            RoundResult::Win => 6,
            RoundResult::Draw => 3,
            RoundResult::Loss => 0,
        };

        choice_score + result_score
    }
}

pub fn parse_choice(choice_str: &str) -> Choice {
    match choice_str.chars().next().unwrap() {
        'A' => Choice::Rock,
        'B' => Choice::Paper,
        'C' => Choice::Scissors,
        'X' => Choice::Rock,
        'Y' => Choice::Paper,
        'Z' => Choice::Scissors,
        _ => panic!("Unknown choice {}", choice_str),
    }
}

pub fn parse_rounds(input: &String) -> Vec<Round> {
    let lines = input.lines();
    let mut rounds = Vec::new();

    for line in lines {
        let (opponent, own) = line.split_once(' ').unwrap();
        rounds.push(Round {
            opponent: parse_choice(opponent),
            own: parse_choice(own),
        });
    }

    rounds
}