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use bevy::prelude::*;
use std::collections::{BTreeMap, BTreeSet};
use std::fs::File;
use std::io::{BufRead, BufReader};
fn main() {
App::build()
.add_resource(WindowDescriptor {
title: "Advent of Code".to_string(),
width: 1920,
height: 1080,
..Default::default()
})
.add_resource(ClearColor(Color::rgb(0., 0., 0.)))
.add_startup_system(setup_camera.system())
.add_startup_system(read_input_file.system())
.add_system(trim_empty_bags.system())
.add_system(add_known_sizes.system())
.add_system(report_gold_bag_known_size.system())
//.add_system(debug_print_bags.system())
.add_plugins(DefaultPlugins)
.run();
}
fn setup_camera(mut commands: Commands) {
commands.spawn(Camera2dComponents::default());
}
const TARGET_COLOUR: &str = "shiny gold";
struct Bag {
colour: String,
required: BTreeMap<String, usize>,
}
struct CantContainShinyGold;
#[derive(Clone)]
struct KnownSize(usize);
fn read_input_file(mut commands: Commands) {
let f = File::open("./inputs/day_7.txt").unwrap();
for line in BufReader::new(f).lines() {
let line = line.unwrap();
let line = line.trim();
let (src_colour, contents) = split_2(line, "bags contain");
let contents_parts = contents
.trim_end_matches('.')
.split(',')
.filter(|part| part != &"no other bags")
.map(|part| {
let (quantity, colour) = split_2(
part.trim().trim_end_matches("bags").trim_end_matches("bag"),
" ",
);
(colour, quantity.parse().unwrap())
})
.collect();
commands.spawn((Bag {
colour: src_colour,
required: contents_parts,
},));
}
}
fn split_2(line: &str, split: &str) -> (String, String) {
let parts = line.splitn(2, split).collect::<Vec<_>>();
assert_eq!(parts.len(), 2);
(parts[0].trim().to_string(), parts[1].trim().to_string())
}
fn debug_print_bags(bags: Query<&Bag>) {
for bag in bags.iter() {
println!("{} requires {:?}", bag.colour, bag.required);
}
}
fn trim_empty_bags(
mut commands: Commands,
bags: Query<Without<CantContainShinyGold, (Entity, &Bag)>>,
) {
let mut colours_cleared = BTreeSet::new();
for (entity, bag) in bags.iter() {
let required_not_relevant = bag.required.keys().all(|required| {
!bags
.iter()
.any(|can_contain_shiny_gold| &can_contain_shiny_gold.1.colour == required)
});
if required_not_relevant && bag.colour != TARGET_COLOUR {
colours_cleared.insert(bag.colour.clone());
commands.insert_one(entity, CantContainShinyGold);
}
}
if colours_cleared.is_empty() {
println!(
"{} bags can hold the shiny gold one",
bags.iter().count() - 1
);
}
}
fn add_known_sizes(mut commands: Commands, bags: Query<(Entity, &Bag, Option<&KnownSize>)>) {
for (entity, bag, size) in bags.iter() {
if size.is_some() {
continue;
}
let mut new_size = Some(0);
for (required_colour, required_quantity) in bag.required.iter() {
if new_size.is_none() {
break;
}
let inner_bag_size = bags
.iter()
.find(|(_, bag, _)| &bag.colour == required_colour)
.and_then(|(_, _, size)| size.clone());
new_size = new_size
.zip(inner_bag_size)
.map(|(a, b)| a + required_quantity * b.0)
}
if let Some(new_size) = new_size {
commands.insert_one(entity, KnownSize(new_size + 1));
}
}
}
fn report_gold_bag_known_size(bags: Query<(&Bag, &KnownSize)>) {
println!("{} have a known size", bags.iter().count());
for (bag, size) in bags.iter() {
if bag.colour == TARGET_COLOUR {
println!("The shiny gold bag must contain {} other bags!", size.0 - 1)
}
}
}
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