🔧 Setup Advent of Code 2021

This year: Elixir! And maybe python.

2021-elixir/.formatter.exs

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

2021-elixir/.gitignore

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+# 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 third-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").
+Aoc-*.tar
+
+# Ignore ElixirLS VS Code extension
+.elixir_ls

2021-elixir/.tool-versions

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+elixir 1.12.0

2021-elixir/README.md

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+# Aoc
+
+Solutions for [Advent of Code 2021][1], this year in Elixir.
+
+[Elixir 1.12.0][2] preferred.
+
+## Help scripts
+
+Run tests using `mix test` as usual. 
+
+Create input file, test file and solution file for a day,
+using day 1 as example:
+
+    mix Aoc.new 1 "Name of the puzzle"
+
+Solve a single puzzle, using puzzle from day 3 as example:
+
+    mix Aoc.solve 3
+
+Solve all puzzles, starting at the first:
+
+    mix Aoc.solve_all
+
+## Log
+
+_Advent of Code has not started yet. See you in December!_
+
+[1]: https://adventofcode.com/
+[2]: https://hexdocs.pm/elixir/Kernel.html

2021-elixir/lib/aoc.ex

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+defmodule Aoc do
+  @year 2021
+  def solve_all() do
+    """
+
+    ADVENT OF CODE #{@year}
+    ===================
+    """
+    |> IO.puts()
+
+    1..25 |> Enum.map(&solve/1)
+  end
+
+  def solve(n) do
+    id = n |> Integer.to_string() |> String.pad_leading(2, "0")
+
+    case File.read("./inputs/" <> id <> ".in") do
+      {:error, _} ->
+        nil
+
+      {:ok, input} ->
+        input
+        |> run(id)
+        |> present
+        |> IO.puts()
+    end
+  end
+
+  def run(input, id) do
+    solution_module = Module.concat(["Aoc.Solution", "Day" <> id])
+
+    data = apply(solution_module, :parse!, [input])
+    name = apply(solution_module, :get_name, [])
+    first_solution = apply(solution_module, :solve_first_part, [data])
+    second_solution = apply(solution_module, :solve_second_part, [data])
+
+    [name, first_solution, second_solution]
+  end
+
+  @doc """
+  Generates a CLI-friendly presentation of the solutions.
+
+  ## Examples
+
+      iex> Aoc.present(["Day 1: tomten kommer", "10", "20"])
+      "Day 1: tomten kommer\\n--------------------\\n\\n1. 10\\n2. 20\\n"
+
+  """
+  def present([name, first_solution, second_solution]) do
+    """
+    #{name}
+    #{1..String.length(name) |> Enum.map_join(fn _x -> "-" end)}
+
+    1. #{first_solution}
+    2. #{second_solution}
+    """
+  end
+end

2021-elixir/lib/mix/tasks/bootstrap.ex

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+defmodule Mix.Tasks.Aoc.New do
+  use Mix.Task
+
+  @shortdoc "Bootstrap new solution"
+  @impl Mix.Task
+
+  @year 2021
+
+  def run([n, name]) do
+    id = n |> String.pad_leading(2, "0")
+
+    input_file = "./inputs/" <> id <> ".in"
+    test_file = "./test/day_" <> id <> "_test.exs"
+    solution_file = "./lib/solutions/day_" <> id <> ".ex"
+
+    IO.puts("Creating " <> input_file)
+    File.touch(input_file)
+
+    IO.puts("Creating " <> test_file)
+    File.write!(test_file, test_file_content(id))
+
+    IO.puts("Creating " <> solution_file)
+    File.write!(solution_file, solution_file_content(name, id, n))
+
+    """
+    \nDone! Start coding.
+
+    Get your puzzle input here:
+    https://adventofcode.com/#{@year}/day/#{n}/input
+
+    mix test                 -- run tests.
+    mix aoc.solve_all        -- run all puzzles, starting with 1
+    mix aoc.solve #{id}         -- run single puzzle, 1-25
+    """
+    |> IO.puts()
+  end
+
+  defp test_file_content(id) do
+    """
+    defmodule Day#{id}Test do
+      use ExUnit.Case
+      doctest Aoc.Solution.Day#{id}
+      import Aoc.Solution.Day#{id}
+
+      test "parses the input" do
+        expected = 10
+
+        assert parse!("10") == expected
+      end
+
+      test "solves first part" do
+        a = "something" |> parse!() |> solve_first_part()
+
+        assert a == :something
+      end
+
+      test "solves second part" do
+        a = "something" |> parse!() |> solve_second_part()
+
+        assert a == :something
+      end
+    end
+    """
+  end
+
+  defp solution_file_content(name, id, n) do
+    ~s"""
+    defmodule Aoc.Solution.Day#{id} do
+      @name "Day #{n}: #{name}"
+      @behaviour Solution
+
+      @impl Solution
+      def get_name, do: @name
+
+      @impl Solution
+      def parse!(_raw) do
+        "10"
+      end
+
+      @impl Solution
+      def solve_first_part(_input) do
+        "(TBW)"
+      end
+
+      @impl Solution
+      def solve_second_part(_input) do
+        "(TBW)"
+      end
+    end
+    """
+  end
+end

2021-elixir/lib/mix/tasks/solve.ex

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+defmodule Mix.Tasks.Aoc.Solve do
+  use Mix.Task
+
+  @shortdoc "Solve single puzzle"
+  @impl Mix.Task
+  def run([id]) do
+    id
+    |> String.to_integer()
+    |> Aoc.solve()
+  end
+end

2021-elixir/lib/mix/tasks/solve_all.ex

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+defmodule Mix.Tasks.Aoc.SolveAll do
+  use Mix.Task
+
+  @shortdoc "Solve all puzzles"
+  @impl Mix.Task
+  def run(_) do
+    Aoc.solve_all()
+  end
+end

2021-elixir/lib/solution.ex

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+defmodule Solution do
+  @callback parse!(String.t()) :: Any
+  @callback get_name() :: String.t()
+  @callback solve_first_part(Any) :: String.t()
+  @callback solve_second_part(Any) :: String.t()
+end

2021-elixir/mix.exs

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+defmodule Aoc.MixProject do
+  use Mix.Project
+
+  def project do
+    [
+      app: :Aoc,
+      version: "0.1.0",
+      elixir: "~> 1.10",
+      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

2021-elixir/test/aoc_test.exs

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+defmodule AocTest do
+  use ExUnit.Case
+  doctest Aoc
+end

2021-elixir/test/test_helper.exs

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+ExUnit.start()

2021-python/.gitignore

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+.idea
+*.pyc
+__pycache__
+.vscode

2021-python/.python-version

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+3.8.0

2021-python/README.md

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+Advent of Code 2021
+===================
+
+Solutions for #aoc2020 in Python 3 (3.8+).
+
+Help scripts
+------------
+
+Solve all puzzles:
+
+    python aoc.py
+    
+To bootstrap a new puzzle (creates `inputs/<day_no>.txt`, `solutions/day_<day_no>.py` och
+`tests/test_day_<day_no>.py`):
+
+    python aoc.py <dag_no> "<puzzle_name>"
+
+Manually copy the puzzle input from https://adventofcode.com and paste it in `inputs/<day_no>.txt`
+to start coding.
+
+Solve separate puzzle (replace `XX` with the puzzle number):
+
+    python -m solutions.day_XX
+
+Run tests (replace `XX` with the puzzle number):
+
+    python -m unittest --locals -v
+    # or, if `pytest` is preferred:
+    pytest

2021-python/aoc.py

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+import sys
+
+year = 2021
+
+try:
+    _, day_no, name = sys.argv
+except ValueError:
+    day_no = None
+    name = None
+
+print(
+    f"\nAdvent of Code {year}"
+    "\n###################"
+    "\n\nby Anders Ytterström (@madr_se)"
+)
+
+if day_no and name:
+    print(f"\n- creating solutions/day_{day_no.zfill(2)}.py")
+    with open("solutions/day_{}.py".format(day_no.zfill(2)), "w") as s:
+        s.write(
+            """
+from solutions import BaseSolution
+
+
+class Solution(BaseSolution):
+    input_file = "{day_no}.txt"
+
+    def __str__(self):
+        return "Day {day}: {name}"
+
+    def parse_input(self, data):
+        return data
+
+    def solve(self, puzzle_input):
+        return True
+
+    def solve_again(self, puzzle_input):
+        return True
+
+
+if __name__ == "__main__":
+    solution = Solution()
+    solution.show_results()
+""".strip().format(
+                day=day_no, day_no=day_no.zfill(2), name=name
+            )
+            + "\n"
+        )
+    print(f"- creating tests/test_day_{day_no.zfill(2)}.py")
+    with open("tests/test_day_{}.py".format(day_no.zfill(2)), "w") as t:
+        t.write(
+            """
+import unittest
+
+from solutions.day_{day_no} import Solution
+
+
+class Day{day_no}TestCase(unittest.TestCase):
+    def setUp(self):
+        self.solution = Solution()
+        self.puzzle_input = self.solution.parse_input(
+            \"\"\"
+        <REPLACE ME>
+        \"\"\"
+        )
+
+    def test_parse_puzzle_input(self):
+        data = \"\"\"
+        <REPLACE ME>
+        \"\"\"
+        assert self.solution.parse_input(data) == "<REPLACE ME>"
+
+    # def test_solve_first_part(self):
+    #     assert self.solution.solve(self.puzzle_input) == True
+
+    # def test_solve_second_part(self):
+    #     assert self.solution.solve_again(self.puzzle_input) == True
+
+
+if __name__ == "__main__":
+    unittest.main()
+""".strip().format(
+                day_no=day_no.zfill(2)
+            )
+            + "\n"
+        )
+    print(f"- creating empty inputs/{day_no.zfill(2)}.txt")
+    with open("inputs/{}.txt".format(day_no.zfill(2)), "w") as i:
+        i.write("")
+
+    print(
+        f"""
+Done! start coding.
+
+Puzzle link:
+https://adventofcode.com/{year}/day/{day_no}
+
+Puzzle input (copy and paste to inputs/{day_no.zfill(2)}.txt):
+https://adventofcode.com/{year}/day/{day_no}/input
+    """
+    )
+    exit(0)
+
+for i in [str(n).zfill(2) for n in range(1, 26)]:
+    try:
+        solution = __import__(
+            "solutions.day_{}".format(i), globals(), locals(), ["Solution"], 0
+        ).Solution()
+        solution.show_results()
+    except IOError:
+        pass
+    except ImportError:
+        pass

2021-python/solutions/__init__.py

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+class BaseSolution:
+    input_file = None
+    trim_input = True
+
+    def read_input(self, filename):
+        filepath = "./inputs/{}".format(filename)
+        with open(filepath, "r") as f:
+            data = f.read()
+            if self.trim_input:
+                return data.strip()
+            return data
+
+    def show_results(self):
+        data = self.read_input(self.input_file)
+        puzzle_input = self.parse_input(data)
+        print(
+            "\n\n{}\n{}\n\nPart 1: {}\nPart 2: {}".format(
+                str(self),
+                "-" * len(str(self)),
+                self.solve(puzzle_input),
+                self.solve_again(puzzle_input),
+            )
+        )
+
+    def solve(self, puzzle_input):
+        raise NotImplemented
+
+    def solve_again(self, puzzle_input):
+        raise NotImplemented
+
+    def parse_input(self, data):
+        raise NotImplemented