New practice exercise square-root

config.json

@@ -2611,6 +2611,23 @@
         ],
         "difficulty": 8
       },
+      {
+        "slug": "square-root",
+        "name": "Square Root",
+        "uuid": "bf9e6251-105b-4fd7-b388-c6f5a652d174",
+        "prerequisites": [
+          "if",
+          "cond",
+          "integer",
+          "multiple-clause-functions",
+          "pattern-matching",
+          "recursion"
+        ],
+        "practices": [
+          "integer"
+        ],
+        "difficulty": 5
+      },
       {
         "slug": "sgf-parsing",
         "name": "SGF Parsing",

exercises/practice/square-root/.docs/instructions.append.md

@@ -0,0 +1,3 @@
+# Introduction append
+
+Make sure that you implement an algorithm that doesn't rely on built-in function such as `:math.sqrt()` or `Float.pow`.

exercises/practice/square-root/.docs/instructions.md

@@ -0,0 +1,9 @@
+# Description
+
+Given a natural radicand, return its square root.
+
+Note that the term "radicand" refers to the number for which the root is to be determined. That is, it is the number under the root symbol.
+
+Check out the Wikipedia pages on [square root](https://en.wikipedia.org/wiki/Square_root) and [methods of computing square roots](https://en.wikipedia.org/wiki/Methods_of_computing_square_roots).
+
+Recall also that natural numbers are positive real whole numbers (i.e. 1, 2, 3 and up).

exercises/practice/square-root/.formatter.exs

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

exercises/practice/square-root/.meta/config.json

@@ -0,0 +1,18 @@
+{
+  "authors": ["jiegillet"],
+  "contributors": [],
+  "files": {
+    "example": [
+      ".meta/example.ex"
+    ],
+    "solution": [
+      "lib/square_root.ex"
+    ],
+    "test": [
+      "test/square_root_test.exs"
+    ]
+  },
+  "blurb": "Given a natural radicand, return its square root.",
+  "source": "wolf99",
+  "source_url": "https://github.com/exercism/problem-specifications/pull/1582"
+}

exercises/practice/square-root/.meta/example.ex

@@ -0,0 +1,22 @@
+defmodule SquareRoot do
+  @doc """
+  Calculate the integer square root of a positive integer
+  """
+  @spec calculate(radicand :: pos_integer) :: pos_integer
+  def calculate(1), do: 1
+
+  def calculate(radicand) do
+    guess = div(radicand, 2)
+    calculate(radicand, guess)
+  end
+
+  def calculate(radicand, guess) do
+    new_guess = div(guess + div(radicand, guess), 2)
+
+    if new_guess == guess do
+      guess
+    else
+      calculate(radicand, new_guess)
+    end
+  end
+end

exercises/practice/square-root/lib/square_root.ex

@@ -0,0 +1,8 @@
+defmodule SquareRoot do
+  @doc """
+  Calculate the integer square root of a positive integer
+  """
+  @spec calculate(radicand :: pos_integer) :: pos_integer
+  def calculate(radicand) do
+  end
+end

exercises/practice/square-root/mix.exs

@@ -0,0 +1,28 @@
+defmodule SquareRoot.MixProject do
+  use Mix.Project
+
+  def project do
+    [
+      app: :square_root,
+      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

exercises/practice/square-root/test/square_root_test.exs

@@ -0,0 +1,57 @@
+defmodule SquareRootTest do
+  use ExUnit.Case
+
+  # @tag :pending
+  test "root of 1" do
+    radicand = 1
+    output = SquareRoot.calculate(radicand)
+    expected = 1
+
+    assert output == expected
+  end
+
+  @tag :pending
+  test "root of 4" do
+    radicand = 4
+    output = SquareRoot.calculate(radicand)
+    expected = 2
+
+    assert output == expected
+  end
+
+  @tag :pending
+  test "root of 25" do
+    radicand = 25
+    output = SquareRoot.calculate(radicand)
+    expected = 5
+
+    assert output == expected
+  end
+
+  @tag :pending
+  test "root of 81" do
+    radicand = 81
+    output = SquareRoot.calculate(radicand)
+    expected = 9
+
+    assert output == expected
+  end
+
+  @tag :pending
+  test "root of 196" do
+    radicand = 196
+    output = SquareRoot.calculate(radicand)
+    expected = 14
+
+    assert output == expected
+  end
+
+  @tag :pending
+  test "root of 65025" do
+    radicand = 65025
+    output = SquareRoot.calculate(radicand)
+    expected = 255
+
+    assert output == expected
+  end
+end

exercises/practice/square-root/test/test_helper.exs

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