aoc2022/two.rs

const SCORE_WIN: u32 = 6;
const SCORE_DRAW: u32 = 3;

const SCORE_ROCK: u32 = 1;
const SCORE_PAPER: u32 = 2;
const SCORE_SCISSORS: u32 = 3;

fn main() {
    let buf = std::fs::read_to_string("two.txt").unwrap();
    let mut total = 0u32;

    for s in buf.split("\n") {
        if s.is_empty() {
            continue;
        }
        let chars = s.chars().collect::<Vec<_>>();
        let opponent = chars[0];
        let result = chars[2];

        let choice = match result {
            'X' => will_lose(opponent),
            'Y' => will_draw(opponent),
            'Z' => will_win(opponent),
            _ => continue,
        };

        total += match result {
            'Y' => SCORE_DRAW,
            'Z' => SCORE_WIN,
            _ => 0,
        };

        total += match choice {
            'A' => SCORE_ROCK,
            'B' => SCORE_PAPER,
            'C' => SCORE_SCISSORS,
            _ => 0,
        };
    }

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

fn will_win(opponent: char) -> char {
    match opponent {
        'A' => 'B',
        'B' => 'C',
        'C' => 'A',
        _ => 'X',
    }
}

fn will_draw(opponent: char) -> char {
    opponent
}

fn will_lose(opponent: char) -> char {
    match opponent {
        'A' => 'C',
        'B' => 'A',
        'C' => 'B',
        _ => 'X',
    }
}