58 lines
2.3 KiB
Rust
58 lines
2.3 KiB
Rust
use std::collections::{BTreeMap, HashMap, HashSet};
|
|
|
|
const INPUT: &str = include_str!("../../data/day21");
|
|
|
|
struct FoodDescription<'a> {
|
|
ingredients: HashSet<&'a str>,
|
|
allergens: HashSet<&'a str>,
|
|
}
|
|
|
|
impl<'a> FoodDescription<'a> {
|
|
fn parse(line: &'a str) -> Self {
|
|
let pos = line.find(" (contains ").unwrap();
|
|
let ingredients = &line[..pos];
|
|
let allergens = line[pos..].strip_prefix(" (contains ").unwrap().strip_suffix(")").unwrap();
|
|
FoodDescription {
|
|
ingredients: ingredients.split_whitespace().collect(),
|
|
allergens: allergens.split(", ").collect(),
|
|
}
|
|
}
|
|
}
|
|
|
|
fn main() {
|
|
let fds = INPUT.lines().map(FoodDescription::parse).collect::<Vec<_>>();
|
|
let allergens: HashSet<&str> = fds.iter().map(|fd| fd.allergens.iter().cloned()).flatten().collect();
|
|
let mut allergen_map_poss: HashMap<&str, HashSet<&str>> = allergens.iter().map(|&a| {
|
|
let mut is = fds.iter()
|
|
.filter(|fd| fd.allergens.contains(a))
|
|
.map(|fd| &fd.ingredients);
|
|
let first_ingr: HashSet<&str> = is.next().unwrap().clone();
|
|
let poss = is.fold(first_ingr, |memo, ingr| {
|
|
memo.intersection(ingr).cloned().collect::<HashSet<_>>()
|
|
});
|
|
(a, poss)
|
|
}).collect();
|
|
let mut allergen_map: BTreeMap<&str, &str> = BTreeMap::new();
|
|
while !allergen_map_poss.is_empty() {
|
|
let (next_allg, next_ingr) = allergen_map_poss.iter().filter_map(|(&a, is)| {
|
|
if is.len() == 1 {
|
|
Some((a, *is.iter().next().unwrap()))
|
|
} else {
|
|
None
|
|
}
|
|
}).next().unwrap();
|
|
allergen_map.insert(next_allg, next_ingr);
|
|
allergen_map_poss.remove(next_allg);
|
|
for ingr in allergen_map_poss.values_mut() {
|
|
ingr.remove(next_ingr);
|
|
}
|
|
}
|
|
println!("Allergens contained by ingredients: {:?}", allergen_map);
|
|
let all_ingredients: HashSet<&str> = allergen_map.values().cloned().collect();
|
|
println!(
|
|
"Ingredients not allergens used {} times",
|
|
fds.iter().map(|fd| fd.ingredients.difference(&all_ingredients).count()).sum::<usize>(),
|
|
);
|
|
println!("Dangerous ingredients: {}", allergen_map.values().cloned().collect::<Vec<_>>().join(","));
|
|
}
|