* add new practice exercise: anagram

config.json

@@ -194,6 +194,14 @@
         "prerequisites": [],
         "difficulty": 8
       },
+      {
+        "slug": "anagram",
+        "name": "Anagram",
+        "uuid": "a4231e93-2e2c-4db2-a073-2b2c30b40185",
+        "practices": [],
+        "prerequisites": [],
+        "difficulty": 8
+      },
       {
         "slug": "armstrong-numbers",
         "name": "Armstrong Numbers",

exercises/practice/anagram/.docs/instructions.append.md

@@ -0,0 +1,24 @@
+# SQLite-specific instructions
+
+* The **candidates** column contains a JSON-encoded list of strings.
+  Example:
+  ```json
+  ["stone","tones","banana","tons","notes","Seton"]
+  ```
+* The **result** column should contain JSON-encoded list of strings as well.
+
+## Table Schema
+
+```sql
+CREATE TABLE anagram (
+  subject    TEXT NOT NULL,
+  candidates TEXT NOT NULL,     -- json array of strings
+  result     TEXT               -- json array of strings
+);
+```
+
+## JSON documentation
+
+[JSON Functions And Operators][json-docs]
+
+[json-docs]: https://www.sqlite.org/json1.htm

exercises/practice/anagram/.docs/instructions.md

@@ -0,0 +1,12 @@
+# Instructions
+
+Given a target word and one or more candidate words, your task is to find the candidates that are anagrams of the target.
+
+An anagram is a rearrangement of letters to form a new word: for example `"owns"` is an anagram of `"snow"`.
+A word is _not_ its own anagram: for example, `"stop"` is not an anagram of `"stop"`.
+
+The target word and candidate words are made up of one or more ASCII alphabetic characters (`A`-`Z` and `a`-`z`).
+Lowercase and uppercase characters are equivalent: for example, `"PoTS"` is an anagram of `"sTOp"`, but `"StoP"` is not an anagram of `"sTOp"`.
+The words you need to find should be taken from the candidate words, using the same letter case.
+
+Given the target `"stone"` and the candidate words `"stone"`, `"tones"`, `"banana"`, `"tons"`, `"notes"`, and `"Seton"`, the anagram words you need to find are `"tones"`, `"notes"`, and `"Seton"`.

exercises/practice/anagram/.docs/introduction.md

@@ -0,0 +1,12 @@
+# Introduction
+
+At a garage sale, you find a lovely vintage typewriter at a bargain price!
+Excitedly, you rush home, insert a sheet of paper, and start typing away.
+However, your excitement wanes when you examine the output: all words are garbled!
+For example, it prints "stop" instead of "post" and "least" instead of "stale."
+Carefully, you try again, but now it prints "spot" and "slate."
+After some experimentation, you find there is a random delay before each letter is printed, which messes up the order.
+You now understand why they sold it for so little money!
+
+You realize this quirk allows you to generate anagrams, which are words formed by rearranging the letters of another word.
+Pleased with your finding, you spend the rest of the day generating hundreds of anagrams.

exercises/practice/anagram/.meta/config.json

@@ -0,0 +1,19 @@
+{
+  "authors": [
+    "jimmytty"
+  ],
+  "files": {
+    "solution": [
+      "anagram.sql"
+    ],
+    "test": [
+      "anagram_test.sql"
+    ],
+    "example": [
+      ".meta/example.sql"
+    ]
+  },
+  "blurb": "Given a word and a list of possible anagrams, select the correct sublist.",
+  "source": "Inspired by the Extreme Startup game",
+  "source_url": "https://github.com/rchatley/extreme_startup"
+}

exercises/practice/anagram/.meta/example.sql

@@ -0,0 +1,43 @@
+DROP TABLE IF EXISTS tmp;
+CREATE TEMPORARY TABLE tmp AS
+  SELECT CAST(word AS TEXT) word FROM (
+    SELECT LOWER(subject) word FROM anagram
+     UNION
+    SELECT LOWER(j.VALUE)
+      FROM anagram, JSON_EACH(candidates) j
+  );
+ALTER TABLE tmp ADD s TEXT;
+UPDATE tmp
+   SET s = (
+     WITH RECURSIVE rcte(word,c) AS (
+       VALUES(word, '')
+       UNION ALL
+       SELECT SUBSTR(word, 2), SUBSTR(word, 1, 1)
+       FROM rcte
+       WHERE LENGTH(word) > 0
+     )
+     SELECT GROUP_CONCAT(c, '')
+       FROM (
+         SELECT c
+           FROM rcte
+          WHERE UNICODE(c) BETWEEN UNICODE('a') AND UNICODE('z')
+          ORDER BY c
+       )
+   );
+
+UPDATE anagram
+   SET result = (
+     SELECT JSON_GROUP_ARRAY(candidate)
+       FROM (
+         SELECT subject, candidate,
+                (SELECT s FROM tmp WHERE LOWER(subject)   = word) AS a,
+                (SELECT s FROM tmp WHERE LOWER(candidate) = word) AS b
+           FROM (
+             SELECT subject,
+                    j.VALUE AS candidate
+               FROM JSON_EACH(candidates) AS j
+           )
+       )
+      WHERE a = b
+        AND LOWER(subject) <> LOWER(candidate)
+   );

exercises/practice/anagram/.meta/tests.toml

@@ -0,0 +1,88 @@
+# 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.
+
+[dd40c4d2-3c8b-44e5-992a-f42b393ec373]
+description = "no matches"
+
+[b3cca662-f50a-489e-ae10-ab8290a09bdc]
+description = "detects two anagrams"
+include = false
+
+[03eb9bbe-8906-4ea0-84fa-ffe711b52c8b]
+description = "detects two anagrams"
+reimplements = "b3cca662-f50a-489e-ae10-ab8290a09bdc"
+
+[a27558ee-9ba0-4552-96b1-ecf665b06556]
+description = "does not detect anagram subsets"
+
+[64cd4584-fc15-4781-b633-3d814c4941a4]
+description = "detects anagram"
+
+[99c91beb-838f-4ccd-b123-935139917283]
+description = "detects three anagrams"
+
+[78487770-e258-4e1f-a646-8ece10950d90]
+description = "detects multiple anagrams with different case"
+
+[1d0ab8aa-362f-49b7-9902-3d0c668d557b]
+description = "does not detect non-anagrams with identical checksum"
+
+[9e632c0b-c0b1-4804-8cc1-e295dea6d8a8]
+description = "detects anagrams case-insensitively"
+
+[b248e49f-0905-48d2-9c8d-bd02d8c3e392]
+description = "detects anagrams using case-insensitive subject"
+
+[f367325c-78ec-411c-be76-e79047f4bd54]
+description = "detects anagrams using case-insensitive possible matches"
+
+[7cc195ad-e3c7-44ee-9fd2-d3c344806a2c]
+description = "does not detect an anagram if the original word is repeated"
+include = false
+
+[630abb71-a94e-4715-8395-179ec1df9f91]
+description = "does not detect an anagram if the original word is repeated"
+reimplements = "7cc195ad-e3c7-44ee-9fd2-d3c344806a2c"
+
+[9878a1c9-d6ea-4235-ae51-3ea2befd6842]
+description = "anagrams must use all letters exactly once"
+
+[85757361-4535-45fd-ac0e-3810d40debc1]
+description = "words are not anagrams of themselves (case-insensitive)"
+include = false
+
+[68934ed0-010b-4ef9-857a-20c9012d1ebf]
+description = "words are not anagrams of themselves"
+reimplements = "85757361-4535-45fd-ac0e-3810d40debc1"
+
+[589384f3-4c8a-4e7d-9edc-51c3e5f0c90e]
+description = "words are not anagrams of themselves even if letter case is partially different"
+reimplements = "85757361-4535-45fd-ac0e-3810d40debc1"
+
+[ba53e423-7e02-41ee-9ae2-71f91e6d18e6]
+description = "words are not anagrams of themselves even if letter case is completely different"
+reimplements = "85757361-4535-45fd-ac0e-3810d40debc1"
+
+[a0705568-628c-4b55-9798-82e4acde51ca]
+description = "words other than themselves can be anagrams"
+include = false
+
+[33d3f67e-fbb9-49d3-a90e-0beb00861da7]
+description = "words other than themselves can be anagrams"
+reimplements = "a0705568-628c-4b55-9798-82e4acde51ca"
+
+[a6854f66-eec1-4afd-a137-62ef2870c051]
+description = "handles case of greek letters"
+include = false
+
+[fd3509e5-e3ba-409d-ac3d-a9ac84d13296]
+description = "different characters may have the same bytes"
+include = false

exercises/practice/anagram/anagram.sql

@@ -0,0 +1,11 @@
+-- Schema: CREATE TABLE anagram (
+--           subject    TEXT NOT NULL,
+--           candidates TEXT NOT NULL,     -- json array of strings
+--           result     TEXT               -- json array of strings
+--         );
+
+-- Task: update the anagram table and set the result based on valid
+--       candidates for the subject field
+--       * the candidates column contains a JSON-encoded list of strings.
+--       * the result column should contain JSON-encoded list of
+--         strings as well.

exercises/practice/anagram/anagram_test.sql

@@ -0,0 +1,43 @@
+-- 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 ./anagram.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 subject, candidates, result FROM anagram) AS actual
+WHERE (actual.subject, actual.candidates, JSON(actual.result)) = (tests.subject, tests.candidates, JSON(tests.expected));
+
+-- Update message for failed tests to give helpful information:
+UPDATE tests
+SET message = (
+    'Result for "'
+    || JSON_OBJECT(
+         'subject',    tests.subject,
+         'candidates', JSON(tests.candidates)
+       )
+    || '"'
+    || ' is <' || COALESCE(actual.result, 'NULL')
+    || '> but should be <' || tests.expected || '>'
+)
+FROM (SELECT subject, candidates, result FROM anagram) AS actual
+WHERE (actual.subject, actual.candidates) = (tests.subject, tests.candidates) 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;

exercises/practice/anagram/create_fixture.sql

@@ -0,0 +1,10 @@
+DROP TABLE IF EXISTS anagram;
+CREATE TABLE anagram (
+  subject    TEXT NOT NULL,
+  candidates TEXT NOT NULL,     -- json array of strings
+  result     TEXT               -- json array of strings
+);
+.mode csv
+.import ./data.csv anagram
+
+UPDATE anagram SET result = NULL;

exercises/practice/anagram/create_test_table.sql

@@ -0,0 +1,35 @@
+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
+    subject    TEXT NOT NULL,
+    candidates TEXT NOT NULL,   -- json array of strings
+    expected   TEXT NOT NULL
+);
+
+INSERT INTO tests (uuid, description, subject, candidates, expected)
+    VALUES
+        ('dd40c4d2-3c8b-44e5-992a-f42b393ec373','no matches','diaper','["hello","world","zombies","pants"]','[]'),
+        ('03eb9bbe-8906-4ea0-84fa-ffe711b52c8b','detects two anagrams','solemn','["lemons","cherry","melons"]','["lemons","melons"]'),
+        ('a27558ee-9ba0-4552-96b1-ecf665b06556','does not detect anagram subsets','good','["dog","goody"]','[]'),
+        ('64cd4584-fc15-4781-b633-3d814c4941a4','detects anagram','listen','["enlists","google","inlets","banana"]','["inlets"]'),
+        ('99c91beb-838f-4ccd-b123-935139917283','detects three anagrams','allergy','["gallery","ballerina","regally","clergy","largely","leading"]','["gallery","regally","largely"]'),
+        ('78487770-e258-4e1f-a646-8ece10950d90','detects multiple anagrams with different case','nose','["Eons","ONES"]','["Eons","ONES"]'),
+        ('1d0ab8aa-362f-49b7-9902-3d0c668d557b','does not detect non-anagrams with identical checksum','mass','["last"]','[]'),
+        ('9e632c0b-c0b1-4804-8cc1-e295dea6d8a8','detects anagrams case-insensitively','Orchestra','["cashregister","Carthorse","radishes"]','["Carthorse"]'),
+        ('b248e49f-0905-48d2-9c8d-bd02d8c3e392','detects anagrams using case-insensitive subject','Orchestra','["cashregister","carthorse","radishes"]','["carthorse"]'),
+        ('f367325c-78ec-411c-be76-e79047f4bd54','detects anagrams using case-insensitive possible matches','orchestra','["cashregister","Carthorse","radishes"]','["Carthorse"]'),
+        ('630abb71-a94e-4715-8395-179ec1df9f91','does not detect an anagram if the original word is repeated','go','["goGoGO"]','[]'),
+        ('9878a1c9-d6ea-4235-ae51-3ea2befd6842','anagrams must use all letters exactly once','tapper','["patter"]','[]'),
+        ('68934ed0-010b-4ef9-857a-20c9012d1ebf','words are not anagrams of themselves','BANANA','["BANANA"]','[]'),
+        ('589384f3-4c8a-4e7d-9edc-51c3e5f0c90e','words are not anagrams of themselves even if letter case is partially different','BANANA','["Banana"]','[]'),
+        ('ba53e423-7e02-41ee-9ae2-71f91e6d18e6','words are not anagrams of themselves even if letter case is completely different','BANANA','["banana"]','[]'),
+        ('33d3f67e-fbb9-49d3-a90e-0beb00861da7','words other than themselves can be anagrams','LISTEN','["LISTEN","Silent"]','["Silent"]');

exercises/practice/anagram/data.csv

@@ -0,0 +1,16 @@
+"diaper","[""hello"",""world"",""zombies"",""pants""]",""
+"solemn","[""lemons"",""cherry"",""melons""]",""
+"good","[""dog"",""goody""]",""
+"listen","[""enlists"",""google"",""inlets"",""banana""]",""
+"allergy","[""gallery"",""ballerina"",""regally"",""clergy"",""largely"",""leading""]",""
+"nose","[""Eons"",""ONES""]",""
+"mass","[""last""]",""
+"Orchestra","[""cashregister"",""Carthorse"",""radishes""]",""
+"Orchestra","[""cashregister"",""carthorse"",""radishes""]",""
+"orchestra","[""cashregister"",""Carthorse"",""radishes""]",""
+"go","[""goGoGO""]",""
+"tapper","[""patter""]",""
+"BANANA","[""BANANA""]",""
+"BANANA","[""Banana""]",""
+"BANANA","[""banana""]",""
+"LISTEN","[""LISTEN"",""Silent""]",""