Add Day1 Part1

.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 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

README.md

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+# AdventOfCode
+
+Run a specific day by executing e.g. `mix run AdventOfCode.Day01.exs`

config/config.exs

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+# 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, key: :value
+#
+# and access this configuration in your application as:
+#
+#     Application.get_env(:advent_of_code, :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"

lib/advent_of_code.ex

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+defmodule AdventOfCode do
+end

lib/day01.exs

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+defmodule AdventOfCode.Day01 do
+  def run do
+    IO.puts "Inverse Captcha: #{solve()}"
+  end
+
+  def solve do
+    input()
+    |> String.codepoints()
+    |> add_first_last()
+    |> sum_if_adjacent(0)
+  end
+
+  def sum_if_adjacent([_], sum), do: sum
+  def sum_if_adjacent([a, a | rest] = list, sum) do
+    {int, ""} = Integer.parse(a)
+    [a | rest]
+    |> sum_if_adjacent(sum + int)
+  end
+  def sum_if_adjacent([a, b | rest] = list, sum) do
+    [b | rest]
+    |> sum_if_adjacent(sum)
+  end
+
+  defp add_first_last([head | _tail] = list) do
+    tsil = list |> Enum.reverse()
+    [head | tsil] |> Enum.reverse()
+  end
+
+  defp input do
+    "lib/inputs/day1_0.txt" |> File.read!() |> String.strip()
+  end
+end
+
+AdventOfCode.Day01.run()

lib/inputs/day1_0.txt

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+237369991482346124663395286354672985457326865748533412179778188397835279584149971999798512279429268727171755461418974558538246429986747532417846157526523238931351898548279549456694488433438982744782258279173323381571985454236569393975735715331438256795579514159946537868358735936832487422938678194757687698143224139243151222475131337135843793611742383267186158665726927967655583875485515512626142935357421852953775733748941926983377725386196187486131337458574829848723711355929684625223564489485597564768317432893836629255273452776232319265422533449549956244791565573727762687439221862632722277129613329167189874939414298584616496839223239197277563641853746193232543222813298195169345186499866147586559781523834595683496151581546829112745533347796213673814995849156321674379644323159259131925444961296821167483628812395391533572555624159939279125341335147234653572977345582135728994395631685618135563662689854691976843435785879952751266627645653981281891643823717528757341136747881518611439246877373935758151119185587921332175189332436522732144278613486716525897262879287772969529445511736924962777262394961547579248731343245241963914775991292177151554446695134653596633433171866618541957233463548142173235821168156636824233487983766612338498874251672993917446366865832618475491341253973267556113323245113845148121546526396995991171739837147479978645166417988918289287844384513974369397974378819848552153961651881528134624869454563488858625261356763562723261767873542683796675797124322382732437235544965647934514871672522777378931524994784845817584793564974285139867972185887185987353468488155283698464226415951583138352839943621294117262483559867661596299753986347244786339543174594266422815794658477629829383461829261994591318851587963554829459353892825847978971823347219468516784857348649693185172199398234123745415271222891161175788713733444497592853221743138324235934216658323717267715318744537689459113188549896737581637879552568829548365738314593851221113932919767844137362623398623853789938824592

mix.exs

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+defmodule AdventOfCode.Mixfile do
+  use Mix.Project
+
+  def project do
+    [
+      app: :advent_of_code,
+      version: "0.1.0",
+      elixir: "~> 1.5",
+      start_permanent: Mix.env == :prod,
+      deps: deps()
+    ]
+  end
+
+  def application do
+    [
+      extra_applications: [:logger]
+    ]
+  end
+
+  defp deps do
+    []
+  end
+end

test/advent_of_code_test.exs

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+defmodule AdventOfCodeTest do
+  use ExUnit.Case
+  doctest AdventOfCode
+end

test/test_helper.exs

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+ExUnit.start()