03

Preparation

Mix.install([:kino])

Part 1

example_diagnostic_report = """
00100
11110
10110
10111
10101
01111
00111
11100
10000
11001
00010
01010
"""

diagnostic_report =
  Kino.Input.textarea("Please input your file:", default: example_diagnostic_report)

data =
  diagnostic_report
  |> Kino.Input.read()
  |> String.split("\n", trim: true)
  |> Enum.map(&String.split(&1, ""))
  |> Enum.map(&Enum.slice(&1, 1..-2))
  |> Enum.map(fn row ->
    row
    |> Enum.map(&String.to_integer/1)
  end)

list_with_frequencies =
  data
  |> Enum.zip()
  |> Enum.map(&Tuple.to_list/1)
  |> Enum.map(&Enum.frequencies/1)
  |> Enum.map(&Map.to_list/1)

[gamma_rate, epsilon_rate] =
  list_with_frequencies
  |> Enum.map(fn [{first_num, first_occur}, {second_num, second_occur}] ->
    if first_occur > second_occur do
      [first_num, second_num]
    else
      [second_num, first_num]
    end
  end)
  |> Enum.zip()
  |> Enum.map(fn digits ->
    digits
    |> Tuple.to_list()
    |> Enum.join()
    |> String.to_integer(2)
  end)

gamma_rate * epsilon_rate