Add 2018 files

2018/elixir/.formatter.exs

@@ -0,0 +1,4 @@
+# Used by "mix format"
+[
+  inputs: ["{mix,.formatter}.exs", "{config,lib,test}/**/*.{ex,exs}"]
+]

2018/elixir/.gitignore

@@ -0,0 +1,26 @@
+# The directory Mix will write compiled artifacts to.
+/_build/
+
+# If you run "mix test --cover", coverage assets end up here.
+/cover/
+
+# The directory Mix downloads your dependencies sources to.
+/deps/
+
+# Where 3rd-party dependencies like ExDoc output generated docs.
+/doc/
+
+# Ignore .fetch files in case you like to edit your project deps locally.
+/.fetch
+
+# If the VM crashes, it generates a dump, let's ignore it too.
+erl_crash.dump
+
+# Also ignore archive artifacts (built via "mix archive.build").
+*.ez
+
+# Ignore package tarball (built via "mix hex.build").
+advent_of_code_2018-*.tar
+
+# Ignore language server files
+/.elixir_ls

2018/elixir/README.md

@@ -0,0 +1,14 @@
+# Advent of Code 2018
+
+Herein lies my Elixir solutions for the Advent of Code 2018 puzzles.
+
+## Approach
+
+My approach to each problem involves the following procedure:
+
+1. Write an initial solution for each puzzle with no help beyond code
+	 documentation.
+2. Rewrite initial solutions to improve the code's readability and performance.
+3. Watch José Valim (the author of Elixir) solve the solutions.
+4. Refactor again, keeping the core of my solution intact (unless truly awful),
+	 but applying anything interesting learned from his solution.

2018/elixir/config/config.exs

@@ -0,0 +1,30 @@
+# This file is responsible for configuring your application
+# and its dependencies with the aid of the Mix.Config module.
+use Mix.Config
+
+# This configuration is loaded before any dependency and is restricted
+# to this project. If another project depends on this project, this
+# file won't be loaded nor affect the parent project. For this reason,
+# if you want to provide default values for your application for
+# 3rd-party users, it should be done in your "mix.exs" file.
+
+# You can configure your application as:
+#
+#     config :advent_of_code_2018, key: :value
+#
+# and access this configuration in your application as:
+#
+#     Application.get_env(:advent_of_code_2018, :key)
+#
+# You can also configure a 3rd-party app:
+#
+#     config :logger, level: :info
+#
+
+# It is also possible to import configuration files, relative to this
+# directory. For example, you can emulate configuration per environment
+# by uncommenting the line below and defining dev.exs, test.exs and such.
+# Configuration from the imported file will override the ones defined
+# here (which is why it is important to import them last).
+#
+#     import_config "#{Mix.env()}.exs"

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2018/elixir/lib/advent_of_code_2018.ex

@@ -0,0 +1,18 @@
+defmodule AdventOfCode2018 do
+  @moduledoc """
+  Documentation for AdventOfCode2018.
+  """
+
+  @doc """
+  Hello world.
+
+  ## Examples
+
+      iex> AdventOfCode2018.hello()
+      :world
+
+  """
+  def hello do
+    :world
+  end
+end

2018/elixir/lib/one.ex

@@ -0,0 +1,16 @@
+defmodule One do
+  def part1(list, initial_freq \\ 0), do: initial_freq + Enum.sum(list)
+
+  def part2(list, initial_freq \\ 0) do
+    list
+    |> Stream.cycle()
+    |> Enum.reduce_while({initial_freq, MapSet.new([initial_freq])}, &part2_reducer/2)
+  end
+
+  def part2_reducer(i, {last, set}) do
+    case (i + last) in set do
+      true -> {:halt, i + last}
+      _ -> {:cont, {i + last, MapSet.put(set, i + last)}}
+    end
+  end
+end

2018/elixir/lib/three.ex

@@ -0,0 +1,73 @@
+defmodule Three do
+  @dimension_parser ~r/\#(\d+)\s@\s(\d+),(\d+):\s(\d+)x(\d+)/
+
+  def part1(input_stream) do
+    input_stream
+    |> Stream.map(&parse_dimensions/1)
+    |> Stream.map(&points_in_square/1)
+    |> Enum.to_list()
+    |> Enum.reduce({MapSet.new([]), MapSet.new([])}, &intersecting_squares/2)
+    |> elem(1)
+    |> MapSet.to_list()
+    |> length()
+  end
+
+  def parse_dimensions(str) do
+    l = Regex.run(@dimension_parser, str)
+    [id, x, y, w, h] = l |> tl() |> Enum.map(&String.to_integer/1)
+    {id, x, y, w, h}
+  end
+
+  def points_in_square({_, x, y, w, h}) do
+    x..(x + w - 1)
+    |> Enum.reduce([], fn x, x_set ->
+      y..(y + h - 1)
+      |> Enum.reduce(x_set, fn y, xy_set ->
+        [{x, y} | xy_set]
+      end)
+    end)
+  end
+
+  def intersecting_squares(square_set, {set, intersects}) do
+    square_set
+    |> Enum.reduce({set, intersects}, fn pos, {set, intersects} ->
+      case MapSet.member?(set, pos) do
+        true -> {set, MapSet.put(intersects, pos)}
+        _ -> {MapSet.put(set, pos), intersects}
+      end
+    end)
+  end
+
+  def intersecting_squares2({id, square_set}, {set, intersects}) do
+    square_set
+    |> Enum.reduce({set, intersects}, fn pos, {set, intersects} ->
+      case MapSet.member?(set, pos) do
+        true -> {set, MapSet.put(intersects, pos)}
+        _ -> {MapSet.put(set, pos), intersects}
+      end
+    end)
+  end
+
+  # parse input lines
+  # for each set of dimensions, check each point in the square
+  #   if the point has been recorded already, remove both ids from the set
+
+  def part2(input_stream) do
+    square_data =
+      input_stream
+      |> Stream.map(&parse_dimensions/1)
+
+    square_id_set =
+      square_data
+      |> Stream.map(&elem(&1, 0))
+      |> Enum.to_list()
+      |> MapSet.new()
+
+    square_data
+    |> Enum.map(&{elem(&1, 0), points_in_square(&1)})
+    |> Enum.reduce({MapSet.new([]), square_id_set}, fn {id, points}, acc -> intersecting_squares2({id, points}, ))
+    |> elem(1)
+    |> MapSet.to_list()
+    |> length()
+  end
+end

2018/elixir/lib/two.ex

@@ -0,0 +1,40 @@
+defmodule Two do
+  def bool_int(true), do: 1
+  def bool_int(false), do: 0
+
+  def part1(id_list) do
+    id_list
+    |> Stream.map(fn id ->
+      id
+      |> String.codepoints()
+      |> Enum.reduce(%{}, fn l, acc -> Map.update(acc, l, 1, &(&1 + 1)) end)
+      |> Map.values()
+      |> MapSet.new()
+    end)
+    |> Enum.to_list()
+    |> Enum.reduce([0, 0], fn s, [x, y] ->
+      [x + bool_int(2 in s), y + bool_int(3 in s)]
+    end)
+    |> Enum.reduce(1, fn i, a -> a * i end)
+  end
+
+  def part2(id_list) do
+    id_list
+    |> Stream.map(&String.trim_trailing/1)
+    |> Enum.to_list()
+    |> permute_all_pairs()
+    |> List.flatten()
+    |> Enum.reduce_while("", fn {id1, id2}, _ ->
+      case String.myers_difference(id1, id2) do
+        [eq: p1, del: <<_x::size(8)>>, ins: <<_y::size(8)>>, eq: p2] -> {:halt, p1 <> p2}
+        _ -> {:cont, ""}
+      end
+    end)
+  end
+
+  def permute_all_pairs([]), do: []
+  def permute_all_pairs(list), do: [permute_pairs(list) | permute_all_pairs(tl(list))]
+
+  def permute_pairs([]), do: []
+  def permute_pairs([cur | rest]), do: Enum.map(rest, &{cur, &1})
+end

2018/elixir/mix.exs

@@ -0,0 +1,28 @@
+defmodule AdventOfCode2018.MixProject do
+  use Mix.Project
+
+  def project do
+    [
+      app: :advent_of_code_2018,
+      version: "0.1.0",
+      elixir: "~> 1.7",
+      start_permanent: Mix.env() == :prod,
+      deps: deps()
+    ]
+  end
+
+  # Run "mix help compile.app" to learn about applications.
+  def application do
+    [
+      extra_applications: [:logger]
+    ]
+  end
+
+  # Run "mix help deps" to learn about dependencies.
+  defp deps do
+    [
+      # {:dep_from_hexpm, "~> 0.3.0"},
+      # {:dep_from_git, git: "https://github.com/elixir-lang/my_dep.git", tag: "0.1.0"},
+    ]
+  end
+end

2018/elixir/test/advent_of_code_2018_test.exs

@@ -0,0 +1,41 @@
+defmodule AdventOfCode2018Test do
+  use ExUnit.Case, async: true
+
+  @doc "https://adventofcode.com/2018/day/1"
+  test "Day 1" do
+    input_stream =
+      File.stream!("./inputs/one.txt", [:read])
+      |> Stream.map(&String.trim_trailing/1)
+      |> Stream.map(&String.to_integer/1)
+
+    assert One.part1(input_stream) == 416
+    assert One.part2(input_stream) == 56752
+  end
+
+  @doc "https://adventofcode.com/2018/day/2"
+  test "Day 2" do
+    input_stream = File.stream!("./inputs/two.txt", [:read])
+
+    assert Two.part1(input_stream) == 6696
+    assert Two.part2(input_stream) == "bvnfawcnyoeyudzrpgslimtkj"
+  end
+
+  @tag :current_day
+  @doc "https://adventofcode.com/2018/day/3"
+  test "Day 3" do
+    test_input =
+      """
+      #1 @ 1,3: 4x4
+      #2 @ 3,1: 4x4
+      #3 @ 5,5: 2x2
+      """
+      |> String.split("\n", trim: true)
+
+    # expected_result = MapSet.new([{4, 4}, {5, 4}, {4, 5}, {5, 5}])
+    expected_result_part1 = 4
+    expected_result_part2 = 3
+
+    assert Three.part1(test_input) == expected_result_part1
+    assert Three.part2(test_input) == expected_result_part2
+  end
+end

2018/elixir/test/test_helper.exs

@@ -0,0 +1 @@
+ExUnit.start()

2019/1.moon

@@ -1,6 +1,7 @@
 -- https://adventofcode.com/2019/day/1
 
 require "common"
+
 input = -> input_for_day(1)\gmatch "%d+"
 
 mass_to_fuel = => -2 + math.floor @ / 3

2019/common.moon

@@ -9,8 +9,8 @@ read_whole_file = =>
 input_for_day = =>
 		read_whole_file "input/#{@}.txt"
 
-reduce = (iterable, initial, f) ->
+reduce = (initial, f) =>
 	acc = initial
-	for e in iterable
+	for e in @
 		acc = f acc, e
 	acc