AdventOfCode/2020/day21/day21part1.exs

42 lines
1.2 KiB
Elixir

defmodule DayDay21Part1 do
def run do
input =
File.read!("input")
|> String.split("\n", trim: true)
|> Enum.map(&String.split(&1, [" (contains ", ", ", ")"], trim: true))
|> Enum.map(fn [ingredients | allergens] -> {String.split(ingredients), allergens} end)
known_allergens =
input
|> Enum.reduce(%{}, fn {ingredients, allergens}, acc ->
ingredients = MapSet.new(ingredients)
Enum.reduce(allergens, acc, fn allergen, acc ->
Map.update(acc, allergen, ingredients, &MapSet.intersection(&1, ingredients))
end)
end)
|> Enum.sort_by(fn {_allergen, ingredients} -> Enum.count(ingredients) end)
all_ingredients = Enum.flat_map(input, fn {ingredients, _allergens} -> ingredients end)
contains_allergens =
known_allergens
|> Enum.map(fn {_allergen, ingredients} -> ingredients end)
|> Enum.reduce(&MapSet.union/2)
no_allergens =
all_ingredients
|> MapSet.new()
|> MapSet.difference(contains_allergens)
|> MapSet.to_list()
all_ingredients
|> Enum.frequencies()
|> Map.take(no_allergens)
|> Map.values()
|> Enum.sum()
|> IO.inspect()
end
end
DayDay21Part1.run()