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