Advent of Code - 2024 - Day 1

Mix.install([
  {:kino, "~> 0.14.2"},
  {:kino_vega_lite, "~> 0.1.13"},
  {:kino_explorer, "~> 0.1.23"}
])

Puzzle Input

puzzle_input = Kino.Input.textarea("Please paste the puzzle input:")

Part 1

part_1_test_input = Kino.Input.textarea("Please paste the test input for part 1:")

part_1_test_input
|> Kino.Input.read()
|> String.split("\n")
|> Enum.reduce({_list1 = [], _list2 = []}, fn pair, {list1, list2} ->
  [a, b] =
    pair
    |> String.split()

  {a, b} = {String.to_integer(a), String.to_integer(b)}
  list1 = [a | list1]
  list2 = [b | list2]
  {list1, list2}
end)
|> then(fn {list1, list2} ->
  list1 = Enum.sort(list1)
  list2 = Enum.sort(list2)

  Enum.zip(list1, list2)
  |> Enum.map(fn {left, right} ->
    abs(left - right)
  end)
  |> Enum.sum()
end)

puzzle_input
|> Kino.Input.read()
|> String.split("\n")
|> Enum.reduce({_list1 = [], _list2 = []}, fn pair, {list1, list2} ->
  [a, b] =
    pair
    |> String.split()

  {a, b} = {String.to_integer(a), String.to_integer(b)}
  list1 = [a | list1]
  list2 = [b | list2]
  {list1, list2}
end)
|> then(fn {list1, list2} ->
  list1 = Enum.sort(list1)
  list2 = Enum.sort(list2)

  Enum.zip(list1, list2)
  |> Enum.map(fn {left, right} ->
    abs(left - right)
  end)
  |> Enum.sum()
end)

Part 2

part_2_test_input = Kino.Input.textarea("Please paste the test input for part 2:")

part_2_test_input
|> Kino.Input.read()
|> String.split("\n")
|> Enum.reduce({_list1 = [], _list2 = []}, fn pair, {list1, list2} ->
  [a, b] =
    pair
    |> String.split()

  {a, b} = {String.to_integer(a), String.to_integer(b)}
  list1 = [a | list1]
  list2 = [b | list2]
  {list1, list2}
end)
|> then(fn {list1, list2} ->
  {
    Enum.reverse(list1),
    Enum.reverse(list2)
  }
end)
|> then(fn {list1, list2} ->
  list2_counts = Enum.frequencies(list2)

  list1
  |> Enum.map(fn left ->
    left * Map.get(list2_counts, left, 0)
  end)
  |> Enum.sum()
end)

puzzle_input
|> Kino.Input.read()
|> String.split("\n")
|> Enum.reduce({_list1 = [], _list2 = []}, fn pair, {list1, list2} ->
  [a, b] =
    pair
    |> String.split()

  {a, b} = {String.to_integer(a), String.to_integer(b)}
  list1 = [a | list1]
  list2 = [b | list2]
  {list1, list2}
end)
|> then(fn {list1, list2} ->
  {
    Enum.reverse(list1),
    Enum.reverse(list2)
  }
end)
|> then(fn {list1, list2} ->
  list2_counts = Enum.frequencies(list2)

  list1
  |> Enum.map(fn left ->
    left * Map.get(list2_counts, left, 0)
  end)
  |> Enum.sum()
end)