use std::collections::HashMap;
use std::error::Error;
use std::fs::File;
use std::io::{self, BufRead};
use std::vec::Vec;

fn main() -> Result<(), Box<dyn Error>> {
    let file = File::open("inputs/day14.txt")?;
    let mut lines = io::BufReader::new(file).lines();

    let mut polymer_template: Vec<char> = lines.next().unwrap().unwrap().chars().collect();
    lines.next();

    let mut rules: HashMap<(char, char), char> = HashMap::new();
    while let Some(Ok(line)) = lines.next() {
        if line == "" {
            break;
        }

        let mut parts = line.split(" -> ");
        let pair = parts.next().unwrap();
        let new = parts.next().unwrap();

        rules.insert(
            (pair.chars().nth(0).unwrap(), pair.chars().nth(1).unwrap()),
            new.chars().nth(0).unwrap(),
        );
    }

    for i in 0..40 {
        let mut next_step: Vec<char> = Vec::new();
        next_step.push(polymer_template[0]);
        for pair in polymer_template.windows(2) {
            //next_step.push(pair[0]);
            if rules.contains_key(&(pair[0], pair[1])) {
                next_step.push(rules[&(pair[0], pair[1])]);
            }
            next_step.push(pair[1]);
        }

        polymer_template = next_step;

        println!("{} : {}", i, polymer_template.len());
    }

    let mut dist: HashMap<char, usize> = HashMap::new();
    for c in polymer_template.iter() {
        let count = dist.get(c).unwrap_or_else(|| &0).clone();
        dist.insert(*c, count + 1);
    }

    let mut counts: Vec<&usize> = dist.values().collect();
    counts.sort();

    println!(
        "Answer1: {}",
        *counts.last().unwrap() - *counts.first().unwrap()
    );

    println!("Answer2: {}", 0);

    Ok(())
}