Day 03

books/aoc/2021/03.livemd

Himanshu Jain

@himanshuinvideo

livebook

More notebooks

Day 03

Mix.install([{:kino, "~> 0.6.2"}])

Input

input = Kino.Input.textarea("Please paste your input")

Part 1

input
|> Kino.Input.read()
|> String.split("\n", trim: true)
|> Enum.map(fn s ->
  String.split(s, "", trim: true)
  |> Enum.map(&amp;String.to_integer/1)
end)
|> Enum.zip_with(fn elements -> elements end)
|> Enum.map(fn list ->
  half = div(length(list), 2)
  zero = list |> Enum.count_until(fn n -> n == 0 end, half + 1)

  gamma = if zero > half, do: 0, else: 1
  epsilon = if zero < half, do: 0, else: 1

  [gamma, epsilon]
end)
|> Enum.zip_with(fn e -> e end)
|> Enum.map(fn el ->
  el |> Enum.join() |> String.to_integer(2)
end)
|> then(fn [gamma, epsilon] -> gamma * epsilon end)

Part 2

input
|> Kino.Input.read()
|> String.split("\n", trim: true)
|> Enum.map(fn s ->
  String.split(s, "", trim: true)
  |> Enum.map(&amp;String.to_integer/1)
end)
|> Enum.zip_with(fn elements -> elements end)
|> Enum.map(fn list ->
  half = div(length(list), 2)
  zero = list |> Enum.count_until(fn n -> n == 0 end, half + 1)

  gamma = if zero > half, do: 0, else: 1
  epsilon = if zero < half, do: 0, else: 1

  [gamma, epsilon]
end)
|> Enum.zip_with(fn e -> e end)
|> Enum.map(fn el ->
  el |> Enum.join() |> String.to_integer(2)
end)
|> then(fn [gamma, epsilon] -> gamma * epsilon end)

Back