Day 10: Elves Look, Elves Say

day_10_elves_look_elves_say.livemd

Eli Chen

@elichen

aoc2015

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Day 10: Elves Look, Elves Say

Section

defmodule P1 do
  def transform(<>) do
    transform(tail, [], 1, head)
    |> Enum.reduce("", fn {num, count}, acc ->
      acc <> Integer.to_string(num) <> Integer.to_string(count)
    end)
  end

  defp transform("", acc, count, char) when char != nil do
    [{count, char - 48} | acc] |> Enum.reverse()
  end

  defp transform(<>, acc, count, head) do
    transform(tail, acc, count + 1, head)
  end

  defp transform(<>, acc, count, char) do
    transform(tail, [{count, char - 48} | acc], 1, head)
  end
end

Enum.reduce(1..40, "3113322113", fn _, acc ->
  P1.transform(acc)
end)
|> String.length()

Enum.reduce(1..50, "3113322113", fn _, acc ->
  P1.transform(acc)
end)
|> String.length()

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