110 lines
3.1 KiB
Rust
110 lines
3.1 KiB
Rust
#[macro_use]
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extern crate lazy_static;
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use std::collections::HashMap;
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use std::default::Default;
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use std::io::{stdin, BufRead};
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use std::sync::Mutex;
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#[derive(Debug, Clone, Copy, Default)]
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struct Element<'a> {
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quantity: usize,
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element: &'a str,
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}
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#[derive(Debug, Clone, Default)]
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struct Reaction<'a> {
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inputs: Vec<Element<'a>>,
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output: Element<'a>,
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}
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impl<'a> From<&'a str> for Element<'a> {
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fn from(other: &'a str) -> Self {
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let mut parts = other.split(' ');
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Element {
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quantity: parts.next().unwrap().parse().unwrap(),
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element: parts.next().unwrap(),
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}
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}
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}
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impl<'a> From<&'a str> for Reaction<'a> {
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fn from(other: &'a str) -> Self {
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let in_out: Vec<_> = other.split(" => ").collect();
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let inputs = in_out[0].split(", ").map(|p| p.into()).collect();
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let output = in_out[1].into();
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Reaction { inputs, output }
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}
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}
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lazy_static! {
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static ref LINES: Vec<String> = stdin().lock().lines().map(|l| l.unwrap()).collect();
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static ref REACTIONS: HashMap<&'static str, Reaction<'static>> = LINES
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.iter()
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.map::<Reaction, _>(|l| l.as_str().into())
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.map(|r| (r.output.element.clone(), r))
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.collect();
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static ref STORAGE: Mutex<HashMap<&'static str, usize>> = Mutex::new(HashMap::new());
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}
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const ORE: &str = "ORE";
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const FUEL: &str = "FUEL";
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fn main() {
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let p1 = count_ingredients(FUEL, 1);
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println!("Part 1: {}", p1);
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println!("Part 2: {}", make_all_the_fuel(p1, 1_000_000_000_000));
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}
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// Not beautiful, but it gets the job done.
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fn make_all_the_fuel(start: usize, limit: usize) -> usize {
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let mut current = start;
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let mut fuel = 1;
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while current < 950_000_000_000 {
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current += count_ingredients(FUEL, 1000);
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fuel += 1000;
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}
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while current < 990_000_000_000 {
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current += count_ingredients(FUEL, 100);
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fuel += 100;
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}
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while current < limit {
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current += count_ingredients(FUEL, 1);
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fuel += 1;
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}
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fuel - 1
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}
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fn count_ingredients(element: &'static str, desired_quantity: usize) -> usize {
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if element == ORE {
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return desired_quantity;
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}
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let mut ores = 0;
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let reaction = REACTIONS.get(&element).unwrap();
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let output_quantity = reaction.output.quantity;
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let num_reactions = (desired_quantity as f32 / output_quantity as f32).ceil() as usize;
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for input in &reaction.inputs {
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let needed = input.quantity * num_reactions;
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let in_storage = get_from_storage(input.element);
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if in_storage >= needed {
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put_into_storage(input.element, in_storage - needed);
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} else {
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put_into_storage(input.element, 0);
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ores += count_ingredients(input.element, needed - in_storage);
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}
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}
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let surplus = (output_quantity * num_reactions) - desired_quantity;
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put_into_storage(element, surplus);
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ores
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}
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#[inline]
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fn get_from_storage(element: &str) -> usize {
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*STORAGE.lock().unwrap().get(element).unwrap_or(&0)
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}
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#[inline]
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fn put_into_storage(element: &'static str, quantity: usize) {
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STORAGE.lock().unwrap().insert(element, quantity);
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}
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