#![allow(dead_code)]
#![allow(unused_variables)]
#![allow(unused_mut)]
use std::collections::HashMap;
use std::env;
use std::fs::File;
use std::io::Read;

fn evolve(s: &Vec<u64>) -> Vec<u64> {
    let mut sn: Vec<u64> = Vec::new();

    for n in s {
        if *n == 0 {
            sn.push(1);
        } else if n.checked_ilog(10).unwrap() % 2 == 1 {
            let pow = 10_u64.pow(n.checked_ilog(10).unwrap() / 2 + 1);
            sn.push(n / pow);
            sn.push(n % pow);
        } else {
            sn.push(n * 2024);
        }
    }
    return sn;
}

fn evolve_fast(n: u64, depth: u64, lut: &mut HashMap<(u64, u64), u64>) -> u64 {
    if depth == 0 {
        return 1;
    }

    if let Some(val) = lut.get(&(n, depth)) {
        return *val;
    }

    let val = if n == 0 {
        evolve_fast(1, depth - 1, lut)
    } else if n.checked_ilog(10).unwrap() % 2 == 1 {
        let pow = 10_u64.pow(n.checked_ilog(10).unwrap() / 2 + 1);
        let a = evolve_fast(n / pow, depth - 1, lut);
        let b = evolve_fast(n % pow, depth - 1, lut);
        a + b
    } else {
        evolve_fast(n * 2024, depth - 1, lut)
    };

    lut.insert((n, depth), val);

    return val;
}

fn main() {
    let args: Vec<String> = env::args().collect();
    let filename = if args.len() == 1 {
        "in/".to_owned() + args[0].split('/').last().unwrap() + ".pzl"
    } else {
        args[1].clone()
    };
    let mut f = File::open(filename).expect("cannot open file");
    let mut content = String::new();
    f.read_to_string(&mut content).expect("cannot read file");
    let line = content.trim_end().split("\n").next().unwrap();

    let stones: Vec<u64> = line.split(" ").map(|a| a.parse().unwrap()).collect();

    let mut s = stones.clone();
    for i in 0..25 {
        s = evolve(&s);
    }
    let res1 = s.len();

    let mut s2 = stones.clone();
    let mut res2 = 0;
    let mut lut = HashMap::new();
    for n in s2 {
        res2 += evolve_fast(n, 75, &mut lut);
    }

    println!("res1: {}", res1);
    println!("res2: {}", res2);
    assert_eq!(res1, 220722);
    assert_eq!(res2, 261952051690787);
}