30 lines
769 B
Elixir
30 lines
769 B
Elixir
|
defmodule Day25Part1 do
|
||
|
|
def run do
|
||
|
|
[card_key, door_key] =
|
||
|
|
File.read!("input")
|
||
|
|
|> String.split("\n", trim: true)
|
||
|
|
|> Enum.map(&String.to_integer/1)
|
||
|
|
|
||
|
|
door_loop_size = find_loop_size(1, door_key, 0)
|
||
|
|
|
||
|
|
transform(1, card_key, door_loop_size)
|
||
|
|
|> IO.puts()
|
||
|
|
end
|
||
|
|
|
||
|
|
def find_loop_size(public_key, public_key, size), do: size
|
||
|
|
|
||
|
|
def find_loop_size(value, key, size) do
|
||
|
|
operation(value, 7) |> find_loop_size(key, size + 1)
|
||
|
|
end
|
||
|
|
|
||
|
|
def transform(encryption_key, _subject_number, 0), do: encryption_key
|
||
|
|
|
||
|
|
def transform(value, subject_number, size) do
|
||
|
|
operation(value, subject_number) |> transform(subject_number, size - 1)
|
||
|
|
end
|
||
|
|
|
||
|
|
def operation(value, subject_number), do: rem(value * subject_number, 2020_12_27)
|
||
|
|
end
|
||
|
|
|
||
|
|
Day25Part1.run()
|