use std::collections::HashMap;

const INPUT: &str = include_str!("../../data/day15");

struct Memory {
    turn: usize,
    mem: HashMap<usize, usize>,
    previous: usize,
}

impl Memory {
    fn new() -> Self {
        Self {
            turn: 0,
            mem: HashMap::new(),
            previous: 0,
        }
    }

    fn remember(&mut self, value: usize) {
        if self.turn > 0 {
            self.mem.insert(self.previous, self.turn);
        }
        self.turn += 1;
        self.previous = value;
    }
}

fn main() {
    let input: Vec<usize> = INPUT.trim().split(",").map(|s| s.parse().unwrap()).collect();
    let mut mem = Memory::new();
    for &value in &input {
        mem.remember(value);
    }
    while mem.turn < 2020 {
        let value = mem.previous;
        if let Some(&turn) = mem.mem.get(&value) {
            mem.remember(mem.turn - turn);
        } else {
            mem.remember(0);
        }
    }
    println!("{}", mem.previous);
    while mem.turn < 30000000 {
        let value = mem.previous;
        if let Some(&turn) = mem.mem.get(&value) {
            mem.remember(mem.turn - turn);
        } else {
            mem.remember(0);
        }
    }
    println!("{}", mem.previous);
}