space age

binary-search/.exercism/config.json

@@ -0,0 +1,31 @@
+{
+  "blurb": "Implement a binary search algorithm.",
+  "authors": [
+    "bernardoamc"
+  ],
+  "contributors": [
+    "angelikatyborska",
+    "Cohen-Carlisle",
+    "devonestes",
+    "lpil",
+    "martinsvalin",
+    "neenjaw",
+    "parkerl",
+    "screamingjungle",
+    "sotojuan",
+    "waiting-for-dev"
+  ],
+  "files": {
+    "solution": [
+      "lib/binary_search.ex"
+    ],
+    "test": [
+      "test/binary_search_test.exs"
+    ],
+    "example": [
+      ".meta/example.ex"
+    ]
+  },
+  "source": "Wikipedia",
+  "source_url": "http://en.wikipedia.org/wiki/Binary_search_algorithm"
+}

binary-search/.exercism/metadata.json

@@ -0,0 +1 @@
+{"track":"elixir","exercise":"binary-search","id":"5e40f287d55a4b898fda154d02e346fe","url":"https://exercism.org/tracks/elixir/exercises/binary-search","handle":"rjNemo","is_requester":true,"auto_approve":false}

binary-search/.formatter.exs

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

binary-search/.gitignore

@@ -0,0 +1,24 @@
+# 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").
+binary_search-*.tar
+

binary-search/HELP.md

@@ -0,0 +1,75 @@
+# Help
+
+## Running the tests
+
+From the terminal, change to the base directory of the exercise then execute the tests with:
+
+```bashv
+$ mix test
+```
+
+This will execute the test file found in the `test` subfolder -- a file ending in `_test.exs`
+
+Documentation:
+
+* [`mix test` - Elixir's test execution tool](https://hexdocs.pm/mix/Mix.Tasks.Test.html)
+* [`ExUnit` - Elixir's unit test library](https://hexdocs.pm/ex_unit/ExUnit.html)
+
+## Pending tests
+
+In test suites of practice exercises, all but the first test have been tagged to be skipped.
+
+Once you get a test passing, you can unskip the next one by commenting out the relevant `@tag :pending` with a `#` symbol.
+
+For example:
+
+```elixir
+# @tag :pending
+test "shouting" do
+  assert Bob.hey("WATCH OUT!") == "Whoa, chill out!"
+end
+```
+
+If you wish to run all tests at once, you can include all skipped test by using the `--include` flag on the `mix test` command:
+
+```bash
+$ mix test --include pending
+```
+
+Or, you can enable all the tests by commenting out the `ExUnit.configure` line in the file `test/test_helper.exs`.
+
+```elixir
+# ExUnit.configure(exclude: :pending, trace: true)
+```
+
+## Useful `mix test` options
+
+* `test/<FILE>.exs:LINENUM` - runs only a single test, the test from `<FILE>.exs` whose definition is on line `LINENUM`
+* `--failed` - runs only tests that failed the last time they ran
+* `--max-failures` - the suite stops evaluating tests when this number of test failures
+is reached
+* `--seed 0` - disables randomization so the tests in a single file will always be ran
+in the same order they were defined in
+
+## Submitting your solution
+
+You can submit your solution using the `exercism submit lib/binary_search.ex` command.
+This command will upload your solution to the Exercism website and print the solution page's URL.
+
+It's possible to submit an incomplete solution which allows you to:
+
+- See how others have completed the exercise
+- Request help from a mentor
+
+## Need to get help?
+
+If you'd like help solving the exercise, check the following pages:
+
+- The [Elixir track's documentation](https://exercism.org/docs/tracks/elixir)
+- [Exercism's support channel on gitter](https://gitter.im/exercism/support)
+- The [Frequently Asked Questions](https://exercism.org/docs/using/faqs)
+
+Should those resources not suffice, you could submit your (incomplete) solution to request mentoring.
+
+If you're stuck on something, it may help to look at some of the [available resources](https://exercism.org/docs/tracks/elixir/resources) out there where answers might be found.
+If you can't find what you're looking for in the documentation, feel free to ask help in the Exercism's BEAM [gitter channel](https://gitter.im/exercism/xerlang).

binary-search/README.md

@@ -0,0 +1,63 @@
+# Binary Search
+
+Welcome to Binary Search on Exercism's Elixir Track.
+If you need help running the tests or submitting your code, check out `HELP.md`.
+
+## Instructions
+
+Implement a binary search algorithm.
+
+Searching a sorted collection is a common task. A dictionary is a sorted
+list of word definitions. Given a word, one can find its definition. A
+telephone book is a sorted list of people's names, addresses, and
+telephone numbers. Knowing someone's name allows one to quickly find
+their telephone number and address.
+
+If the list to be searched contains more than a few items (a dozen, say)
+a binary search will require far fewer comparisons than a linear search,
+but it imposes the requirement that the list be sorted.
+
+In computer science, a binary search or half-interval search algorithm
+finds the position of a specified input value (the search "key") within
+an array sorted by key value.
+
+In each step, the algorithm compares the search key value with the key
+value of the middle element of the array.
+
+If the keys match, then a matching element has been found and its index,
+or position, is returned.
+
+Otherwise, if the search key is less than the middle element's key, then
+the algorithm repeats its action on the sub-array to the left of the
+middle element or, if the search key is greater, on the sub-array to the
+right.
+
+If the remaining array to be searched is empty, then the key cannot be
+found in the array and a special "not found" indication is returned.
+
+A binary search halves the number of items to check with each iteration,
+so locating an item (or determining its absence) takes logarithmic time.
+A binary search is a dichotomic divide and conquer search algorithm.
+
+## Source
+
+### Created by
+
+- @bernardoamc
+
+### Contributed to by
+
+- @angelikatyborska
+- @Cohen-Carlisle
+- @devonestes
+- @lpil
+- @martinsvalin
+- @neenjaw
+- @parkerl
+- @screamingjungle
+- @sotojuan
+- @waiting-for-dev
+
+### Based on
+
+Wikipedia - http://en.wikipedia.org/wiki/Binary_search_algorithm

binary-search/lib/binary_search.ex

@@ -0,0 +1,35 @@
+defmodule BinarySearch do
+  @doc """
+    Searches for a key in the tuple using the binary search algorithm.
+    It returns :not_found if the key is not in the tuple.
+    Otherwise returns {:ok, index}.
+
+    ## Examples
+
+      iex> BinarySearch.search({}, 2)
+      :not_found
+
+      iex> BinarySearch.search({1, 3, 5}, 2)
+      :not_found
+
+      iex> BinarySearch.search({1, 3, 5}, 5)
+      {:ok, 2}
+
+  """
+
+  @spec search(tuple, integer) :: {:ok, integer} | :not_found
+  def search({key}, key), do: {:ok, 0}
+
+  def search(numbers, key) do
+    count = tuple_size(numbers)
+    mid = div(count, 2)
+    {left, right} = numbers |> Tuple.to_list() |> Enum.split(mid)
+
+    cond do
+      key > List.last(left) -> search(right, key)
+      key < hd(right) -> search(left, key)
+    end
+  end
+
+  # def search(_, _), do: :not_found
+end

binary-search/mix.exs

@@ -0,0 +1,28 @@
+defmodule BinarySearch.MixProject do
+  use Mix.Project
+
+  def project do
+    [
+      app: :binary_search,
+      version: "0.1.0",
+      # elixir: "~> 1.8",
+      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

binary-search/test/binary_search_test.exs

@@ -0,0 +1,65 @@
+defmodule BinarySearchTest do
+  use ExUnit.Case
+
+  test "finds a value in a tuple with one element" do
+    assert BinarySearch.search({6}, 6) == {:ok, 0}
+    assert BinarySearch.search({3}, 3) == {:ok, 0}
+  end
+
+  test "finds a value in the middle of a tuple" do
+    assert BinarySearch.search({1, 2, 3, 4, 5, 6}, 4) == {:ok, 2}
+    assert BinarySearch.search({1, 3, 4, 6, 8, 9, 11}, 6) == {:ok, 3}
+  end
+
+  test "finds a value at the beginning of a tuple" do
+    assert BinarySearch.search({1, 2, 4, 5, 6}, 1) == {:ok, 0}
+    assert BinarySearch.search({1, 3, 4, 5, 8, 9, 11}, 1) == {:ok, 0}
+  end
+
+  @tag :pending
+  test "finds a value at the end of a tuple" do
+    assert BinarySearch.search({1, 2, 4, 5, 6}, 6) == {:ok, 4}
+    assert BinarySearch.search({1, 3, 4, 5, 8, 9, 11}, 11) == {:ok, 6}
+  end
+
+  @tag :pending
+  test "finds a value in a tuple of odd length" do
+    tuple = {1, 3, 5, 8, 13, 21, 34, 55, 89, 144, 233, 377, 634}
+    assert BinarySearch.search(tuple, 144) == {:ok, 9}
+  end
+
+  @tag :pending
+  test "finds a value in a tuple of even length" do
+    tuple = {1, 3, 5, 8, 13, 21, 34, 55, 89, 144, 233, 377}
+    assert BinarySearch.search(tuple, 21) == {:ok, 5}
+    assert BinarySearch.search(tuple, 34) == {:ok, 6}
+  end
+
+  @tag :pending
+  test "identifies that a value is not included in the tuple" do
+    assert BinarySearch.search({2, 4, 6}, 3) == :not_found
+    assert BinarySearch.search({1, 3, 4, 6, 8, 9, 11}, 7) == :not_found
+  end
+
+  @tag :pending
+  test "a value smaller than the tuple's smallest value is not found" do
+    assert BinarySearch.search({2, 4, 6}, 1) == :not_found
+    assert BinarySearch.search({1, 3, 4, 6, 8, 9, 11}, 0) == :not_found
+  end
+
+  @tag :pending
+  test "a value larger than the tuple's largest value is not found" do
+    assert BinarySearch.search({2, 4, 6}, 9) == :not_found
+    assert BinarySearch.search({1, 3, 4, 6, 8, 9, 11}, 13) == :not_found
+  end
+
+  @tag :pending
+  test "nothing is found in an empty tuple" do
+    assert BinarySearch.search({}, 1) == :not_found
+  end
+
+  @tag :pending
+  test "nothing is found when the left and right bounds cross" do
+    assert BinarySearch.search({1, 2}, 0) == :not_found
+  end
+end

binary-search/test/test_helper.exs

@@ -0,0 +1,2 @@
+ExUnit.start()
+ExUnit.configure(exclude: :pending, trace: true)

resistor-color-duo/.exercism/config.json

@@ -0,0 +1,18 @@
+{
+  "authors": ["jiegillet"],
+  "contributors": [],
+  "files": {
+    "example": [
+      ".meta/example.ex"
+    ],
+    "solution": [
+      "lib/resistor_color_duo.ex"
+    ],
+    "test": [
+      "test/resistor_color_duo_test.exs"
+    ]
+  },
+  "blurb": "Convert color codes, as used on resistors, to a numeric value.",
+  "source": "Maud de Vries, Erik Schierboom",
+  "source_url": "https://github.com/exercism/problem-specifications/issues/1464"
+}

resistor-color-duo/.formatter.exs

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

resistor-color-duo/HELP.md

@@ -0,0 +1,75 @@
+# Help
+
+## Running the tests
+
+From the terminal, change to the base directory of the exercise then execute the tests with:
+
+```bash
+$ mix test
+```
+
+This will execute the test file found in the `test` subfolder -- a file ending in `_test.exs`
+
+Documentation:
+
+* [`mix test` - Elixir's test execution tool](https://hexdocs.pm/mix/Mix.Tasks.Test.html)
+* [`ExUnit` - Elixir's unit test library](https://hexdocs.pm/ex_unit/ExUnit.html)
+
+## Pending tests
+
+In test suites of practice exercises, all but the first test have been tagged to be skipped.
+
+Once you get a test passing, you can unskip the next one by commenting out the relevant `@tag :pending` with a `#` symbol.
+
+For example:
+
+```elixir
+# @tag :pending
+test "shouting" do
+  assert Bob.hey("WATCH OUT!") == "Whoa, chill out!"
+end
+```
+
+If you wish to run all tests at once, you can include all skipped test by using the `--include` flag on the `mix test` command:
+
+```bash
+$ mix test --include pending
+```
+
+Or, you can enable all the tests by commenting out the `ExUnit.configure` line in the file `test/test_helper.exs`.
+
+```elixir
+# ExUnit.configure(exclude: :pending, trace: true)
+```
+
+## Useful `mix test` options
+
+* `test/<FILE>.exs:LINENUM` - runs only a single test, the test from `<FILE>.exs` whose definition is on line `LINENUM`
+* `--failed` - runs only tests that failed the last time they ran
+* `--max-failures` - the suite stops evaluating tests when this number of test failures
+is reached
+* `--seed 0` - disables randomization so the tests in a single file will always be ran
+in the same order they were defined in
+
+## Submitting your solution
+
+You can submit your solution using the `exercism submit lib/resistor_color_duo.ex` command.
+This command will upload your solution to the Exercism website and print the solution page's URL.
+
+It's possible to submit an incomplete solution which allows you to:
+
+- See how others have completed the exercise
+- Request help from a mentor
+
+## Need to get help?
+
+If you'd like help solving the exercise, check the following pages:
+
+- The [Elixir track's documentation](https://exercism.org/docs/tracks/elixir)
+- [Exercism's support channel on gitter](https://gitter.im/exercism/support)
+- The [Frequently Asked Questions](https://exercism.org/docs/using/faqs)
+
+Should those resources not suffice, you could submit your (incomplete) solution to request mentoring.
+
+If you're stuck on something, it may help to look at some of the [available resources](https://exercism.org/docs/tracks/elixir/resources) out there where answers might be found.
+If you can't find what you're looking for in the documentation, feel free to ask help in the Exercism's BEAM [gitter channel](https://gitter.im/exercism/xerlang).

resistor-color-duo/README.md

@@ -0,0 +1,48 @@
+# Resistor Color Duo
+
+Welcome to Resistor Color Duo on Exercism's Elixir Track.
+If you need help running the tests or submitting your code, check out `HELP.md`.
+
+## Instructions
+
+If you want to build something using a Raspberry Pi, you'll probably use _resistors_.
+For this exercise, you need to know two things about them:
+
+* Each resistor has a resistance value.
+* Resistors are small - so small in fact that if you printed the resistance value on them, it would be hard to read.
+
+To get around this problem, manufacturers print color-coded bands onto the resistors to denote their resistance values.
+Each band has a position and a numeric value.
+
+The first 2 bands of a resistor have a simple encoding scheme: each color maps to a single number.
+For example, if they printed a brown band (value 1) followed by a green band (value 5), it would translate to the number 15.
+
+In this exercise you are going to create a helpful program so that you don't have to remember the values of the bands.
+The program will take color names as input and output a two digit number, even if the input is more than two colors!
+
+The band colors are encoded as follows:
+
+* Black: 0
+* Brown: 1
+* Red: 2
+* Orange: 3
+* Yellow: 4
+* Green: 5
+* Blue: 6
+* Violet: 7
+* Grey: 8
+* White: 9
+
+From the example above:
+brown-green should return 15
+brown-green-violet should return 15 too, ignoring the third color.
+
+## Source
+
+### Created by
+
+- @jiegillet
+
+### Based on
+
+Maud de Vries, Erik Schierboom - https://github.com/exercism/problem-specifications/issues/1464

resistor-color-duo/_build/test/lib/resistor_color_duo/ebin/resistor_color_duo.app

@@ -0,0 +1,6 @@
+{application,resistor_color_duo,
+             [{applications,[kernel,stdlib,elixir,logger]},
+              {description,"resistor_color_duo"},
+              {modules,['Elixir.ResistorColorDuo']},
+              {registered,[]},
+              {vsn,"0.1.0"}]}.

resistor-color-duo/lib/resistor_color_duo.ex

@@ -0,0 +1,26 @@
+defmodule ResistorColorDuo do
+  @colors %{
+    black: 0,
+    brown: 1,
+    red: 2,
+    orange: 3,
+    yellow: 4,
+    green: 5,
+    blue: 6,
+    violet: 7,
+    grey: 8,
+    white: 9
+  }
+
+  @doc """
+  Calculate a resistance value from two colors
+  """
+  @spec value(colors :: [atom]) :: integer
+  def value(colors),
+    do:
+      colors
+      |> Enum.take(2)
+      |> Enum.map(&Map.get(@colors, &1))
+      |> Enum.join()
+      |> String.to_integer()
+end

resistor-color-duo/mix.exs

@@ -0,0 +1,28 @@
+defmodule ResistorColorDuo.MixProject do
+  use Mix.Project
+
+  def project do
+    [
+      app: :resistor_color_duo,
+      version: "0.1.0",
+      # elixir: "~> 1.8",
+      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

resistor-color-duo/test/resistor_color_duo_test.exs

@@ -0,0 +1,60 @@
+defmodule ResistorColorDuoTest do
+  use ExUnit.Case
+
+  # @tag :pending
+  test "Brown and black" do
+    colors = [:brown, :black]
+    output = ResistorColorDuo.value(colors)
+    expected = 10
+
+    assert output == expected
+  end
+
+  test "Blue and grey" do
+    colors = [:blue, :grey]
+    output = ResistorColorDuo.value(colors)
+    expected = 68
+
+    assert output == expected
+  end
+
+  test "Yellow and violet" do
+    colors = [:yellow, :violet]
+    output = ResistorColorDuo.value(colors)
+    expected = 47
+
+    assert output == expected
+  end
+
+  test "White and red" do
+    colors = [:white, :red]
+    output = ResistorColorDuo.value(colors)
+    expected = 92
+
+    assert output == expected
+  end
+
+  test "Orange and orange" do
+    colors = [:orange, :orange]
+    output = ResistorColorDuo.value(colors)
+    expected = 33
+
+    assert output == expected
+  end
+
+  test "Ignore additional colors" do
+    colors = [:green, :brown, :orange]
+    output = ResistorColorDuo.value(colors)
+    expected = 51
+
+    assert output == expected
+  end
+
+  test "Black and brown, one digit" do
+    colors = [:black, :brown]
+    output = ResistorColorDuo.value(colors)
+    expected = 1
+
+    assert output == expected
+  end
+end

resistor-color-duo/test/test_helper.exs

@@ -0,0 +1,2 @@
+ExUnit.start()
+ExUnit.configure(exclude: :pending, trace: true)

resistor-color/lib/resistor_color.ex

@@ -14,6 +14,7 @@ defmodule ResistorColor do
     grey: 8,
     white: 9
   }
+
   @doc """
   Return the value of a color band
   """

space-age/.exercism/config.json

@@ -0,0 +1,36 @@
+{
+  "blurb": "Given an age in seconds, calculate how old someone is in terms of a given planet's solar years.",
+  "authors": [
+    "rubysolo"
+  ],
+  "contributors": [
+    "angelikatyborska",
+    "Cohen-Carlisle",
+    "dalexj",
+    "devonestes",
+    "henrik",
+    "jinyeow",
+    "koriroys",
+    "kytrinyx",
+    "lpil",
+    "neenjaw",
+    "parkerl",
+    "pminten",
+    "sotojuan",
+    "Teapane",
+    "waiting-for-dev"
+  ],
+  "files": {
+    "solution": [
+      "lib/space_age.ex"
+    ],
+    "test": [
+      "test/space_age_test.exs"
+    ],
+    "example": [
+      ".meta/example.ex"
+    ]
+  },
+  "source": "Partially inspired by Chapter 1 in Chris Pine's online Learn to Program tutorial.",
+  "source_url": "http://pine.fm/LearnToProgram/?Chapter=01"
+}

space-age/.exercism/metadata.json

@@ -0,0 +1 @@
+{"track":"elixir","exercise":"space-age","id":"9a81858ebd7c46a4a47952bd1535102e","url":"https://exercism.org/tracks/elixir/exercises/space-age","handle":"rjNemo","is_requester":true,"auto_approve":false}

space-age/.formatter.exs

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

space-age/.gitignore

@@ -0,0 +1,24 @@
+# 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").
+space_age-*.tar
+

space-age/HELP.md

@@ -0,0 +1,75 @@
+# Help
+
+## Running the tests
+
+From the terminal, change to the base directory of the exercise then execute the tests with:
+
+```bash
+$ mix test
+```
+
+This will execute the test file found in the `test` subfolder -- a file ending in `_test.exs`
+
+Documentation:
+
+* [`mix test` - Elixir's test execution tool](https://hexdocs.pm/mix/Mix.Tasks.Test.html)
+* [`ExUnit` - Elixir's unit test library](https://hexdocs.pm/ex_unit/ExUnit.html)
+
+## Pending tests
+
+In test suites of practice exercises, all but the first test have been tagged to be skipped.
+
+Once you get a test passing, you can unskip the next one by commenting out the relevant `@tag :pending` with a `#` symbol.
+
+For example:
+
+```elixir
+# @tag :pending
+test "shouting" do
+  assert Bob.hey("WATCH OUT!") == "Whoa, chill out!"
+end
+```
+
+If you wish to run all tests at once, you can include all skipped test by using the `--include` flag on the `mix test` command:
+
+```bash
+$ mix test --include pending
+```
+
+Or, you can enable all the tests by commenting out the `ExUnit.configure` line in the file `test/test_helper.exs`.
+
+```elixir
+# ExUnit.configure(exclude: :pending, trace: true)
+```
+
+## Useful `mix test` options
+
+* `test/<FILE>.exs:LINENUM` - runs only a single test, the test from `<FILE>.exs` whose definition is on line `LINENUM`
+* `--failed` - runs only tests that failed the last time they ran
+* `--max-failures` - the suite stops evaluating tests when this number of test failures
+is reached
+* `--seed 0` - disables randomization so the tests in a single file will always be ran
+in the same order they were defined in
+
+## Submitting your solution
+
+You can submit your solution using the `exercism submit lib/space_age.ex` command.
+This command will upload your solution to the Exercism website and print the solution page's URL.
+
+It's possible to submit an incomplete solution which allows you to:
+
+- See how others have completed the exercise
+- Request help from a mentor
+
+## Need to get help?
+
+If you'd like help solving the exercise, check the following pages:
+
+- The [Elixir track's documentation](https://exercism.org/docs/tracks/elixir)
+- [Exercism's support channel on gitter](https://gitter.im/exercism/support)
+- The [Frequently Asked Questions](https://exercism.org/docs/using/faqs)
+
+Should those resources not suffice, you could submit your (incomplete) solution to request mentoring.
+
+If you're stuck on something, it may help to look at some of the [available resources](https://exercism.org/docs/tracks/elixir/resources) out there where answers might be found.
+If you can't find what you're looking for in the documentation, feel free to ask help in the Exercism's BEAM [gitter channel](https://gitter.im/exercism/xerlang).

space-age/README.md

@@ -0,0 +1,51 @@
+# Space Age
+
+Welcome to Space Age on Exercism's Elixir Track.
+If you need help running the tests or submitting your code, check out `HELP.md`.
+
+## Instructions
+
+Given an age in seconds, calculate how old someone would be on:
+
+- Mercury: orbital period 0.2408467 Earth years
+- Venus: orbital period 0.61519726 Earth years
+- Earth: orbital period 1.0 Earth years, 365.25 Earth days, or 31557600 seconds
+- Mars: orbital period 1.8808158 Earth years
+- Jupiter: orbital period 11.862615 Earth years
+- Saturn: orbital period 29.447498 Earth years
+- Uranus: orbital period 84.016846 Earth years
+- Neptune: orbital period 164.79132 Earth years
+
+So if you were told someone were 1,000,000,000 seconds old, you should
+be able to say that they're 31.69 Earth-years old.
+
+If you're wondering why Pluto didn't make the cut, go watch [this
+YouTube video](http://www.youtube.com/watch?v=Z_2gbGXzFbs).
+
+## Source
+
+### Created by
+
+- @rubysolo
+
+### Contributed to by
+
+- @angelikatyborska
+- @Cohen-Carlisle
+- @dalexj
+- @devonestes
+- @henrik
+- @jinyeow
+- @koriroys
+- @kytrinyx
+- @lpil
+- @neenjaw
+- @parkerl
+- @pminten
+- @sotojuan
+- @Teapane
+- @waiting-for-dev
+
+### Based on
+
+Partially inspired by Chapter 1 in Chris Pine's online Learn to Program tutorial. - http://pine.fm/LearnToProgram/?Chapter=01

space-age/lib/space_age.ex

@@ -0,0 +1,40 @@
+defmodule SpaceAge do
+  @type planet ::
+          :mercury
+          | :venus
+          | :earth
+          | :mars
+          | :jupiter
+          | :saturn
+          | :uranus
+          | :neptune
+
+  @seconds_in_earth_year 31_557_600
+  @seconds_in_mercury_year 0.2408467 * @seconds_in_earth_year
+  @seconds_in_venus_year 0.61519726 * @seconds_in_earth_year
+  @seconds_in_mars_year 1.8808158 * @seconds_in_earth_year
+  @seconds_in_jupiter_year 11.862615 * @seconds_in_earth_year
+  @seconds_in_saturn_year 29.447498 * @seconds_in_earth_year
+  @seconds_in_uranus_year 84.016846 * @seconds_in_earth_year
+  @seconds_in_neptune_year 164.79132 * @seconds_in_earth_year
+
+  @doc """
+  Return the number of years a person that has lived for 'seconds' seconds is
+  aged on 'planet', or an error if 'planet' is not a planet.
+  """
+  @spec age_on(planet, pos_integer) :: {:ok, float} | {:error, String.t()}
+  def age_on(planet, seconds) do
+    case planet do
+      :mercury -> {:ok, seconds / @seconds_in_mercury_year}
+      :venus -> {:ok, seconds / @seconds_in_venus_year}
+      :earth -> {:ok, seconds / @seconds_in_earth_year}
+      :mars -> {:ok, seconds / @seconds_in_mars_year}
+      :jupiter -> {:ok, seconds / @seconds_in_jupiter_year}
+      :saturn -> {:ok, seconds / @seconds_in_saturn_year}
+      :uranus -> {:ok, seconds / @seconds_in_uranus_year}
+      :neptune -> {:ok, seconds / @seconds_in_neptune_year}
+      # sorry pluto
+      _ -> {:error, "not a planet"}
+    end
+  end
+end

space-age/mix.exs

@@ -0,0 +1,28 @@
+defmodule SpaceAge.MixProject do
+  use Mix.Project
+
+  def project do
+    [
+      app: :space_age,
+      version: "0.1.0",
+      # elixir: "~> 1.8",
+      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

space-age/test/space_age_test.exs

@@ -0,0 +1,70 @@
+defmodule SpaceAgeTest do
+  use ExUnit.Case
+
+  test "age on Earth" do
+    input = 1_000_000_000
+    {:ok, age} = SpaceAge.age_on(:earth, input)
+    assert_in_delta 31.69, age, 0.005
+  end
+
+  test "age on Mercury" do
+    input = 2_134_835_688
+    {:ok, age} = SpaceAge.age_on(:earth, input)
+    assert_in_delta 67.65, age, 0.005
+    {:ok, age} = SpaceAge.age_on(:mercury, input)
+    assert_in_delta 280.88, age, 0.005
+  end
+
+  test "age on Venus" do
+    input = 189_839_836
+    {:ok, age} = SpaceAge.age_on(:earth, input)
+    assert_in_delta 6.02, age, 0.005
+    {:ok, age} = SpaceAge.age_on(:venus, input)
+    assert_in_delta 9.78, age, 0.005
+  end
+
+  test "age on Mars" do
+    input = 2_129_871_239
+    {:ok, age} = SpaceAge.age_on(:earth, input)
+    assert_in_delta 67.49, age, 0.005
+    {:ok, age} = SpaceAge.age_on(:mars, input)
+    assert_in_delta 35.88, age, 0.005
+  end
+
+  test "age on Jupiter" do
+    input = 901_876_382
+    {:ok, age} = SpaceAge.age_on(:earth, input)
+    assert_in_delta 28.58, age, 0.005
+    {:ok, age} = SpaceAge.age_on(:jupiter, input)
+    assert_in_delta 2.41, age, 0.005
+  end
+
+  test "age on Saturn" do
+    input = 2_000_000_000
+    {:ok, age} = SpaceAge.age_on(:earth, input)
+    assert_in_delta 63.38, age, 0.005
+    {:ok, age} = SpaceAge.age_on(:saturn, input)
+    assert_in_delta 2.15, age, 0.005
+  end
+
+  test "age on Uranus" do
+    input = 1_210_123_456
+    {:ok, age} = SpaceAge.age_on(:earth, input)
+    assert_in_delta 38.35, age, 0.005
+    {:ok, age} = SpaceAge.age_on(:uranus, input)
+    assert_in_delta 0.46, age, 0.005
+  end
+
+  test "age on Neptune" do
+    input = 1_821_023_456
+    {:ok, age} = SpaceAge.age_on(:earth, input)
+    assert_in_delta 57.70, age, 0.005
+    {:ok, age} = SpaceAge.age_on(:neptune, input)
+    assert_in_delta 0.35, age, 0.005
+  end
+
+  test "invalid planet causes error" do
+    input = 680_804_807
+    assert SpaceAge.age_on(:sun, input) == {:error, "not a planet"}
+  end
+end

space-age/test/test_helper.exs

@@ -0,0 +1,2 @@
+ExUnit.start()
+ExUnit.configure(exclude: :pending, trace: true)