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Solution modules

A solution for a day is written in a solution module. These modules are written using the AOC.aoc/3 macro.

import aoc

aoc <year>, <day> do
  def p1(input) do
    # part 1 solution goes here
  end

  def p2(input) do
    # part 2 solution goes here
  end

  def another_function do
    # arbitrary code goes here
  end

  # any code that is valid in an
  # elixir module is valid here
end

This generates a standard elixir module named Y<year>.D<day>.

iex interaction

Inside iex, you can use the functions described in AOC.IEx to test your solution:

Test solutions

• AOC.IEx.p1e/1
• AOC.IEx.p1i/1
• AOC.IEx.p2e/1
• AOC.IEx.p2i/1

Get module (to test helpers)

• AOC.IEx.mod/1

Get puzzle / example data

• AOC.IEx.input_path/1
• AOC.IEx.example_path/1
• AOC.IEx.input_string/1
• AOC.IEx.example_string/1
• AOC.IEx.input_stream/1
• AOC.IEx.example_stream/1

Mix tasks

mix is used to fetch the input for a puzzle and to create boilerplate code.

Fetch input / example

• mix aoc.get

Generate code skeleton

• mix aoc.gen

Fetch + Generate

• mix aoc

In iex

iex> p1i()
# Runs p1 of the current day
# with the input string of that day
iex> p1i(day: 8)
# Runs p1 of day 8 of the current
# year with the input string of that day
iex> p1i(day: 8, year: 1991)
# Runs p1 of day 8 of 1991
# with the input string of that day
iex> p1i(year: 1991)
# Uses the current day of the month,
# but in 1991

A day can be specified like this for all AOC.IEx functions. The only exception are the AOC.IEx.p1/2 and AOC.IEx.p2/2 functions:

iex> p1(nil, day: 8)
# Calls Y<current year>.D8.p1()
iex> p1(something, day: 8)
# Calls Y<current year>.D8.p1(something)

This is done to maintain backwards compatibility with the alternative solution module style described below.

Specifying year or day in config.exs

Year or day may also be specified in the config/config.exs file:

import Config

config :advent_of_code_utils,
  day: 8,
  year: 1991

Setting the year is, for instance, useful when going back to finish previous years.

When using mix tasks

• mix aoc --day <day> --year <year>
  • Generates code + fetches input for the given year and day.
• mix aoc -d <day> -y <year>
  • Same as above, but shorter.
• mix aoc --day <day>
  • Generates code + fetches input for the current year with the given day.
• mix aoc --year <year>
  • Generates code + fetches input for the given year with the current day.

The same options can be passed to mix aoc.gen and mix aoc.get.

Precedence

Mix tasks and the AOC.IEx helpers use the year and date from the following sources, using the first that matches.

1. Options passed as argument to a function or as a flag to a mix task.
2. Year or day as specified in the application configuration (i.e. in config/config.exs).
3. The local year and month of day.

Solution modules

import aoc

aoc <year>, <day> do
  def p1 do
    input_stream() # or others
    |> # part 1 solution goes here
  end

  def p2 do
    example_stream() # or others
    |> # part 2 solution goes here
  end

  # Overriding is possible to avoid boilerplate
  def input_stream, do
    super() |> Stream.map(&String.to_integer/1)
  end
end

Helpers

The generated helpers all call a function defined in AOC with the year and day of the solution module.

iex interaction

Test solutions

• AOC.IEx.p1/2
• AOC.IEx.p2/2

Get module (to test helpers)

• AOC.IEx.mod/1