Advent of code 2025 day 9

Mix.install([
  {:kino, "~> 0.18"}
])

Part 1

https://adventofcode.com/2025/day/9

input = Kino.Input.textarea("Please give me input:")

points =
  Kino.Input.read(input)
  |> String.split("\n", trim: true)
  |> Enum.map(fn xy ->
    [x, y] =
      String.split(xy, ",")
      |> Enum.map(&String.to_integer/1)

    {x, y}
  end)

length(points)

defmodule Part1 do
  def calc_max_area(points) do
    # Make a distance table, requires (N^2 - N) / 2 calculations
    # Double loop, where inner loop p-inner <> p-outer
    # To prevent too much double calculations, p-inner < p-outer
    # output: [{distance1, p1, p2}, ...]
    for p1 = {x1, y1} <- points,
        p2 = {x2, y2} <- points,
        p1 < p2 do
      dx = abs(x2 - x1) + 1
      dy = abs(y2 - y1) + 1

      area = dx * dy
      {area, p1, p2}
    end
    |> Enum.map(&amp;elem(&amp;1, 0))
    |> Enum.max()
  end

end

IO.inspect Part1.calc_max_area(points), label: "part1"