Day 15

Mix.install([
  {:kino, "~> 0.7.0"}
])

IEx.Helpers.c("/Users/johnb/dev/2022adventOfCode/advent_of_code.ex")
alias AdventOfCode, as: AOC
alias Kino.Input

# Note: when making the next template, something like this works well:
#   `cat day04.livemd | sed 's/03/04/' > day04.livemd`
#

Installation and Data

input_p1example = Kino.Input.textarea("Example Data")

input_p1puzzleInput = Kino.Input.textarea("Puzzle Input")

input_source_select =
  Kino.Input.select("Source", [{:example, "example"}, {:puzzle_input, "puzzle input"}])

p1data = fn ->
  (Kino.Input.read(input_source_select) == :example &&
     Kino.Input.read(input_p1example)) ||
    Kino.Input.read(input_p1puzzleInput)
end

Part 1

###

Sensor at x=2, y=18: closest beacon is at x=-2, y=15 (4+)
Sensor at x=9, y=16: closest beacon is at x=10, y=16
Sensor at x=13, y=2: closest beacon is at x=15, y=3
Sensor at x=12, y=14: closest beacon is at x=10, y=16
Sensor at x=10, y=20: closest beacon is at x=10, y=16
Sensor at x=14, y=17: closest beacon is at x=10, y=16
Sensor at x=8, y=7: closest beacon is at x=2, y=10
Sensor at x=2, y=0: closest beacon is at x=2, y=10
Sensor at x=0, y=11: closest beacon is at x=2, y=10
Sensor at x=20, y=14: closest beacon is at x=25, y=17
Sensor at x=17, y=20: closest beacon is at x=21, y=22
Sensor at x=16, y=7: closest beacon is at x=15, y=3
Sensor at x=14, y=3: closest beacon is at x=15, y=3
Sensor at x=20, y=1: closest beacon is at x=15, y=3

###

defmodule Day15 do
  def taxi_dist([sx, sy, bx, by]), do: abs(sx - bx) + abs(sy - by)

  def exes(rules) do
    Enum.map(rules, fn r -> [r.sx, r.bx] end) |> List.flatten()
  end

  def eyes(rules) do
    Enum.map(rules, fn r -> [r.sy, r.by] end) |> List.flatten()
  end

  @sensor_statement ~r/Sensor at x=(.+), y=(.+): closest beacon is at x=(.+), y=(.+)$/
  def solve(text) do
    rules =
      text
      |> AOC.as_single_lines()
      |> Enum.map(fn line ->
        [_line | rest] = Regex.run(@sensor_statement, line)
        [sx, sy, bx, by] = Enum.map(rest, &String.to_integer/1)
        %{sx: sx, sy: sy, bx: bx, by: by, taxi_dist: taxi_dist([sx, sy, bx, by])}
      end)
      |> IO.inspect()

    {left, right} = Enum.min_max(exes(rules))
    {top, bottom} = Enum.min_max(eyes(rules))

    _extents = %{
      left: left,
      right: right,
      top: top,
      bottom: bottom,
      dx: right - left,
      dy: bottom - top
    }

    # on row y=2000000, from -888612 to 4807592,
    # how many of the 5696204 spots cannot have a beacon?
    # For each rule, what area does it span on 2000000?
    # How many of these overlap?
    # line = 10
    line = 2_000_000

    [span0 | spans] =
      rules
      |> Enum.reject(fn rule -> abs(line - rule.sy) > rule.taxi_dist end)
      |> Enum.map(fn rule ->
        distance_from_sensor = abs(line - rule.sy)
        side_extent = rule.taxi_dist - distance_from_sensor
        [rule.sx - side_extent, rule.sx + side_extent]
      end)
      |> Enum.sort()
      |> IO.inspect(label: "Started with #{Enum.count(rules)} rules")

    # |> Enum.count()

    Enum.reduce(spans, [span0], fn [x1, x2], [[xa, xb] | rest] = acc ->
      IO.inspect([[x1, x2], [[xa, xb], rest]], label: "?????")

      cond do
        x1 <= xb and x2 <= xb -> acc
        x1 <= xb -> [[xa, x2] | rest]
        true -> [[x1, x2] | acc]
      end
      |> IO.inspect(label: "spans")
    end)
  end

  def solve2(_text) do
  end
end

p1data.()
|> Day15.solve()
|> IO.inspect(label: "\n*** Part 1 solution (example: )")

# extents:
# %{bottom: 22, dx: 27, dy: 22, left: -2, right: 25, top: 0}
# %{bottom: 4625568, dx: 5696204, dy: 4563942, left: -888612, right: 4807592, top: 61626}
# 3519824 (3552294 - 32470) is too low

# p1data.()
# |> Day15.solve2()
# |> IO.inspect(label: "\n*** Part 2 solution (example: )")

#

Part Two