Add practice exercise: square-root

config.json

@@ -234,6 +234,14 @@
         "prerequisites": [],
         "difficulty": 5
       },
+      {
+        "slug": "square-root",
+        "name": "Square Root",
+        "uuid": "3fa9b650-df9f-457f-bfa0-51b62696f998",
+        "practices": [],
+        "prerequisites": [],
+        "difficulty": 5
+      },
       {
         "slug": "swift-scheduling",
         "name": "Swift Scheduling",

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

@@ -0,0 +1,18 @@
+# Instructions
+
+Your task is to calculate the square root of a given number.
+
+- Try to avoid using the pre-existing math libraries of your language.
+- As input you'll be given a positive whole number, i.e. 1, 2, 3, 4…
+- You are only required to handle cases where the result is a positive whole number.
+
+Some potential approaches:
+
+- Linear or binary search for a number that gives the input number when squared.
+- Successive approximation using Newton's or Heron's method.
+- Calculating one digit at a time or one bit at a time.
+
+You can check out the Wikipedia pages on [integer square root][integer-square-root] and [methods of computing square roots][computing-square-roots] to help with choosing a method of calculation.
+
+[integer-square-root]: https://en.wikipedia.org/wiki/Integer_square_root
+[computing-square-roots]: https://en.wikipedia.org/wiki/Methods_of_computing_square_roots

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

@@ -0,0 +1,10 @@
+# Introduction
+
+We are launching a deep space exploration rocket and we need a way to make sure the navigation system stays on target.
+
+As the first step in our calculation, we take a target number and find its square root (that is, the number that when multiplied by itself equals the target number).
+
+The journey will be very long.
+To make the batteries last as long as possible, we had to make our rocket's onboard computer very power efficient.
+Unfortunately that means that we can't rely on fancy math libraries and functions, as they use more power.
+Instead we want to implement our own square root calculation.

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

@@ -0,0 +1,19 @@
+{
+  "authors": [
+    "jimmytty"
+  ],
+  "files": {
+    "solution": [
+      "square-root.sql"
+    ],
+    "test": [
+      "square-root_test.sql"
+    ],
+    "example": [
+      ".meta/example.sql"
+    ]
+  },
+  "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.sql

@@ -0,0 +1,16 @@
+UPDATE "square-root"
+   SET result = (
+     WITH RECURSIVE isqrt (number, approx) AS (
+       VALUES (radicand, radicand)
+       UNION ALL
+       SELECT number, (number / approx + approx) / 2
+         FROM isqrt
+        WHERE approx * approx != NUMBER
+          AND  approx > 1
+     )
+     SELECT approx AS sqrt
+       FROM isqrt
+      ORDER BY approx ASC
+      LIMIT 1
+   )
+;

exercises/practice/square-root/.meta/tests.toml

@@ -0,0 +1,28 @@
+# This is an auto-generated file.
+#
+# Regenerating this file via `configlet sync` will:
+# - Recreate every `description` key/value pair
+# - Recreate every `reimplements` key/value pair, where they exist in problem-specifications
+# - Remove any `include = true` key/value pair (an omitted `include` key implies inclusion)
+# - Preserve any other key/value pair
+#
+# As user-added comments (using the # character) will be removed when this file
+# is regenerated, comments can be added via a `comment` key.
+
+[9b748478-7b0a-490c-b87a-609dacf631fd]
+description = "root of 1"
+
+[7d3aa9ba-9ac6-4e93-a18b-2e8b477139bb]
+description = "root of 4"
+
+[6624aabf-3659-4ae0-a1c8-25ae7f33c6ef]
+description = "root of 25"
+
+[93beac69-265e-4429-abb1-94506b431f81]
+description = "root of 81"
+
+[fbddfeda-8c4f-4bc4-87ca-6991af35360e]
+description = "root of 196"
+
+[c03d0532-8368-4734-a8e0-f96a9eb7fc1d]
+description = "root of 65025"

exercises/practice/square-root/create_fixture.sql

@@ -0,0 +1,10 @@
+DROP TABLE IF EXISTS "square-root";
+CREATE TABLE "square-root" (
+    radicand INTEGER NOT NULL,
+    result   INTEGER
+);
+
+.mode csv
+.import ./data.csv "square-root"
+
+UPDATE "square-root" SET result = NULL;

exercises/practice/square-root/create_test_table.sql

@@ -0,0 +1,24 @@
+DROP TABLE IF EXISTS tests;
+CREATE TABLE IF NOT EXISTS tests (
+    -- uuid and description are taken from the test.toml file
+    uuid TEXT PRIMARY KEY,
+    description TEXT NOT NULL,
+    -- The following section is needed by the online test-runner
+    status TEXT DEFAULT 'fail',
+    message TEXT,
+    output TEXT,
+    test_code TEXT,
+    task_id INTEGER DEFAULT NULL,
+    -- Here are columns for the actual tests
+    radicand INTEGER NOT NULL,
+    expected INTEGER NOT NULL
+);
+
+INSERT INTO tests (uuid, description, radicand, expected)
+    VALUES
+        ('9b748478-7b0a-490c-b87a-609dacf631fd', 'root of 1', 1, 1),
+        ('7d3aa9ba-9ac6-4e93-a18b-2e8b477139bb', 'root of 4', 4, 2),
+        ('6624aabf-3659-4ae0-a1c8-25ae7f33c6ef', 'root of 25', 25, 5),
+        ('93beac69-265e-4429-abb1-94506b431f81', 'root of 81', 81, 9),
+        ('fbddfeda-8c4f-4bc4-87ca-6991af35360e', 'root of 196', 196, 14),
+        ('c03d0532-8368-4734-a8e0-f96a9eb7fc1d', 'root of 65025', 65025, 255);

exercises/practice/square-root/data.csv

@@ -0,0 +1,6 @@
+1,
+4,
+25,
+81,
+196,
+65025,

exercises/practice/square-root/square-root.sql

@@ -0,0 +1,7 @@
+-- Schema:
+-- CREATE TABLE "square-root" (
+--     radicand INTEGER NOT NULL,
+--     result   INTEGER
+-- );
+--
+-- Task: update the square-root table and set the result based on the radicand.

exercises/practice/square-root/square-root_test.sql

@@ -0,0 +1,40 @@
+-- Create database:
+.read ./create_fixture.sql
+
+-- Read user student solution and save any output as markdown in user_output.md:
+.mode markdown
+.output user_output.md
+.read ./square-root.sql
+.output
+
+-- Create a clean testing environment:
+.read ./create_test_table.sql
+
+-- Comparison of user input and the tests updates the status for each test:
+UPDATE tests
+SET status = 'pass'
+FROM (SELECT radicand, result FROM "square-root") AS actual
+WHERE (actual.radicand, actual.result) = (tests.radicand, tests.expected);
+
+-- Update message for failed tests to give helpful information:
+UPDATE tests
+SET message = (
+    'Result for "'
+    || tests.radicand
+    || '"'
+    || ' is <' || COALESCE(actual.result, 'NULL')
+    || '> but should be <' || tests.expected || '>'
+)
+FROM (SELECT radicand, result FROM "square-root") AS actual
+WHERE actual.radicand = tests.radicand AND tests.status = 'fail';
+
+-- Save results to ./output.json (needed by the online test-runner)
+.mode json
+.once './output.json'
+SELECT description, status, message, output, test_code, task_id
+FROM tests;
+
+-- Display test results in readable form for the student:
+.mode table
+SELECT description, status, message
+FROM tests;