use std::env::args;
use std::fs::File;
use std::io::BufRead;
use std::io::BufReader;

fn get_data() -> (u8, u8) {
    let path = args().nth(1).unwrap();
    let file = File::open(path).unwrap();

    let mut state = 0;
    let mut player1 = 0;
    let mut player2 = 0;

    for line in BufReader::new(file).lines() {
        match state {
            0 => {
                player1 = line.unwrap()[28..].parse::<u8>().unwrap();
                state = 1;
            },
            1 => {
                player2 = line.unwrap()[28..].parse::<u8>().unwrap();
                state = 2;
            },
            _ => unreachable!(),
        }
    }

    return (player1 - 1, player2 - 1);
}

fn index(pos1: u8, pos2: u8, score1: u8, score2: u8) -> usize {
    return usize::from(pos1)
        + usize::from(pos2) * 10
        + usize::from(score1) * 10 * 10
        + usize::from(score2) * 10 * 10 * 21;
}

fn play_dirac(pos1: u8, pos2: u8, score1: u8, score2: u8, mut cache: &mut [Option<(u64, u64)>; 10 * 10 * 21 * 21]) -> (u64, u64) {
    // https://neddit.ce9e.org/r/adventofcode/comments/rl6p8y/2021_day_21_solutions/hpeokw2/
    if score2 >= 21 {
        return (0, 1);
    }

    let i = index(pos1, pos2, score1, score2);
    match cache[i] {
        None => {},
        Some(v) => return v,
    }

    let mut wins1 = 0;
    let mut wins2 = 0;

    for a in [1, 2, 3].iter() {
        for b in [1, 2, 3].iter() {
            for c in [1, 2, 3].iter() {
                let pos = (pos1 + a + b + c) % 10;
                let score = score1 + (pos + 1);
                // switch players
                let (w2, w1) = play_dirac(pos2, pos, score2, score, &mut cache);
                wins1 += w1;
                wins2 += w2;
            }
        }
    }

    cache[i] = Some((wins1, wins2));

    return (wins1, wins2);
}

fn main() {
    let (pos1, pos2) = get_data();
    let mut cache = [None; 10 * 10 * 21 * 21];
    let (wins1, wins2) = play_dirac(pos1, pos2, 0, 0, &mut cache);

    if wins1 > wins2 {
        println!("{}", wins1);
    } else {
        println!("{}", wins2);
    }
}