32 lines
964 B
Crystal
32 lines
964 B
Crystal
require "advent"
|
|
input = input(2020, 21).lines.map do |line|
|
|
data = line.match(/^([a-z ]+) \(contains (.+)\)$/).not_nil!
|
|
{data[1].split(" ").to_set, data[2].split(", ").to_set}
|
|
end
|
|
|
|
allergens = input.flat_map(&.last.to_a).to_set
|
|
ingredients = input.flat_map(&.first.to_a).to_set
|
|
|
|
allergen_sets = {} of String => Set(String)
|
|
allergens.each do |a|
|
|
input.each do |ings, als|
|
|
next unless als.includes? a
|
|
allergen_sets[a] ||= ings
|
|
allergen_sets[a] &= ings
|
|
end
|
|
end
|
|
|
|
safe = ingredients.reject { |i| allergen_sets.any? &.last.includes?(i) }
|
|
puts "Part 1: #{input.sum &.first.count { |i| safe.includes? i }}"
|
|
|
|
known_allergens = {} of String => String
|
|
while allergen_sets.size > known_allergens.size
|
|
allergen_sets.each do |a, s|
|
|
next unless s.size == 1
|
|
new_known = s.first
|
|
known_allergens[a] = new_known
|
|
allergen_sets.each &.last.delete(new_known)
|
|
end
|
|
end
|
|
puts "Part 2: #{known_allergens.to_a.sort_by(&.first).map(&.last).join(",")}"
|