Advent of Code 2023 Day 11 Part 1

Mix.install([
  {:kino_aoc, "~> 0.1.5"}
])

Get Inputs

{:ok, puzzle_input} =
  KinoAOC.download_puzzle("2023", "11", System.fetch_env!("LB_SESSION"))

My answer

defmodule Resolver do
  def parse(input) do
    orig_space =
      input
      |> String.split("\n")
      |> Enum.with_index()
      |> Enum.map(fn {line, row} ->
        line
        |> String.codepoints()
        |> Enum.with_index()
        |> Enum.filter(fn {cell, _} -> cell == "#" end)
        |> Enum.map(fn {_, col} -> {row, col} end)
      end)
      |> Enum.concat()

    max_row =
      orig_space
      |> Enum.map(fn {row, _} -> row end)
      |> Enum.max()

    max_col =
      orig_space
      |> Enum.map(fn {col, _} -> col end)
      |> Enum.max()

    empty_rows =
      0..max_row
      |> Enum.filter(fn target_row ->
        orig_space
        |> Enum.map(fn {row, _} -> row end)
        |> Enum.member?(target_row)
        |> Kernel.!()
      end)

    empty_cols =
      0..max_col
      |> Enum.filter(fn target_col ->
        orig_space
        |> Enum.map(fn {_, col} -> col end)
        |> Enum.member?(target_col)
        |> Kernel.!()
      end)

    orig_space
    |> Enum.map(fn {row, col} ->
      ex_rows = Enum.count(empty_rows, fn empty_row -> row > empty_row end)
      ex_cols = Enum.count(empty_cols, fn empty_col -> col > empty_col end)

      {row + ex_rows, col + ex_cols}
    end)
  end

  def resolve(space) do
    space
    |> Enum.with_index()
    |> Enum.map(fn {{src_row, src_col}, src_index} ->
      space
      |> Enum.with_index()
      |> Enum.map(fn {{dst_row, dst_col}, dst_index} ->
        if src_index >= dst_index do
          0
        else
          abs(dst_row - src_row) + abs(dst_col - src_col)
        end
      end)
      |> Enum.sum()
    end)
    |> Enum.sum()
  end
end

maze =
  """
  ...#......
  .......#..
  #.........
  ..........
  ......#...
  .#........
  .........#
  ..........
  .......#..
  #...#.....
  """
  |> String.slice(0..-2)
  |> Resolver.parse()

Resolver.resolve(maze)

maze = Resolver.parse(puzzle_input)

Resolver.resolve(maze)