Add practice exercise: queen-attack

config.json

@@ -274,6 +274,14 @@
         "prerequisites": [],
         "difficulty": 5
       },
+      {
+        "slug": "queen-attack",
+        "name": "Queen Attack",
+        "uuid": "f452c4fd-9ee7-49d6-b373-bc250445b4c8",
+        "practices": [],
+        "prerequisites": [],
+        "difficulty": 5
+      },
       {
         "slug": "resistor-color-trio",
         "name": "Resistor Color Trio",

exercises/practice/queen-attack/.docs/instructions.md

@@ -0,0 +1,21 @@
+# Instructions
+
+Given the position of two queens on a chess board, indicate whether or not they are positioned so that they can attack each other.
+
+In the game of chess, a queen can attack pieces which are on the same row, column, or diagonal.
+
+A chessboard can be represented by an 8 by 8 array.
+
+So if you are told the white queen is at `c5` (zero-indexed at column 2, row 3) and the black queen at `f2` (zero-indexed at column 5, row 6), then you know that the set-up is like so:
+
+![A chess board with two queens. Arrows emanating from the queen at c5 indicate possible directions of capture along file, rank and diagonal.](https://assets.exercism.org/images/exercises/queen-attack/queen-capture.svg)
+
+You are also able to answer whether the queens can attack each other.
+In this case, that answer would be yes, they can, because both pieces share a diagonal.
+
+## Credit
+
+The chessboard image was made by [habere-et-dispertire][habere-et-dispertire] using LaTeX and the [chessboard package][chessboard-package] by Ulrike Fischer.
+
+[habere-et-dispertire]: https://exercism.org/profiles/habere-et-dispertire
+[chessboard-package]: https://github.com/u-fischer/chessboard

exercises/practice/queen-attack/.meta/config.json

@@ -0,0 +1,19 @@
+{
+  "authors": [
+    "jimmytty"
+  ],
+  "files": {
+    "solution": [
+      "queen-attack.sql"
+    ],
+    "test": [
+      "queen-attack_test.sql"
+    ],
+    "example": [
+      ".meta/example.sql"
+    ]
+  },
+  "blurb": "Given the position of two queens on a chess board, indicate whether or not they are positioned so that they can attack each other.",
+  "source": "J Dalbey's Programming Practice problems",
+  "source_url": "https://users.csc.calpoly.edu/~jdalbey/103/Projects/ProgrammingPractice.html"
+}

exercises/practice/queen-attack/.meta/example.sql

@@ -0,0 +1,55 @@
+UPDATE "queen-attack"
+   SET error =
+       CASE
+       WHEN white_row < 0 OR black_row < 0 THEN 'row not positive'
+       WHEN white_row > 7 OR black_row > 7 THEN 'row not on board'
+       WHEN white_col < 0 OR black_col < 0 THEN 'column not positive'
+       WHEN white_col > 7 OR black_col > 7 THEN 'column not on board'
+       END
+;
+
+UPDATE "queen-attack"
+   SET result = (
+     WITH
+       seq AS (SELECT value FROM GENERATE_SERIES(0, 7)),
+       positions (row, col) AS (
+       SELECT white_row, value FROM seq
+        UNION
+       SELECT value, white_col FROM seq
+        UNION
+       SELECT white_row - value AS r, white_col - value AS c
+         FROM seq
+        WHERE r >= 0 AND c >= 0
+        UNION
+       SELECT white_row + value AS r, white_col + value AS c
+         FROM seq
+        WHERE r <= 7 AND c <= 7
+        UNION
+       SELECT white_row - value AS r, white_col - value AS c
+         FROM seq
+        WHERE r >= 0 AND c >= 0
+        UNION
+       SELECT white_row + value AS r, white_col + value AS c
+         FROM seq
+        WHERE r <= 7 AND c <= 7
+        UNION
+       SELECT white_row + value AS r, white_col - value AS c
+         FROM seq
+        WHERE r <= 7 AND c >= 0
+        UNION
+       SELECT white_row - value AS r, white_col + value AS c
+         FROM seq
+        WHERE r >= 0 AND c <= 7
+     )
+     SELECT
+       COALESCE(
+         (SELECT TRUE
+            FROM positions
+           WHERE row = black_row
+             AND col = black_col
+         ),
+         FALSE
+       )
+   )
+ WHERE error ISNULL
+;

exercises/practice/queen-attack/.meta/tests.toml

@@ -0,0 +1,49 @@
+# 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.
+
+[3ac4f735-d36c-44c4-a3e2-316f79704203]
+description = "Test creation of Queens with valid and invalid positions -> queen with a valid position"
+
+[4e812d5d-b974-4e38-9a6b-8e0492bfa7be]
+description = "Test creation of Queens with valid and invalid positions -> queen must have positive row"
+
+[f07b7536-b66b-4f08-beb9-4d70d891d5c8]
+description = "Test creation of Queens with valid and invalid positions -> queen must have row on board"
+
+[15a10794-36d9-4907-ae6b-e5a0d4c54ebe]
+description = "Test creation of Queens with valid and invalid positions -> queen must have positive column"
+
+[6907762d-0e8a-4c38-87fb-12f2f65f0ce4]
+description = "Test creation of Queens with valid and invalid positions -> queen must have column on board"
+
+[33ae4113-d237-42ee-bac1-e1e699c0c007]
+description = "Test the ability of one queen to attack another -> cannot attack"
+
+[eaa65540-ea7c-4152-8c21-003c7a68c914]
+description = "Test the ability of one queen to attack another -> can attack on same row"
+
+[bae6f609-2c0e-4154-af71-af82b7c31cea]
+description = "Test the ability of one queen to attack another -> can attack on same column"
+
+[0e1b4139-b90d-4562-bd58-dfa04f1746c7]
+description = "Test the ability of one queen to attack another -> can attack on first diagonal"
+
+[ff9b7ed4-e4b6-401b-8d16-bc894d6d3dcd]
+description = "Test the ability of one queen to attack another -> can attack on second diagonal"
+
+[0a71e605-6e28-4cc2-aa47-d20a2e71037a]
+description = "Test the ability of one queen to attack another -> can attack on third diagonal"
+
+[0790b588-ae73-4f1f-a968-dd0b34f45f86]
+description = "Test the ability of one queen to attack another -> can attack on fourth diagonal"
+
+[543f8fd4-2597-4aad-8d77-cbdab63619f8]
+description = "Test the ability of one queen to attack another -> cannot attack if falling diagonals are only the same when reflected across the longest falling diagonal"

exercises/practice/queen-attack/create_fixture.sql

@@ -0,0 +1,14 @@
+DROP TABLE IF EXISTS "queen-attack";
+CREATE TABLE "queen-attack" (
+  white_row INTEGER NOT NULL,
+  white_col INTEGER NOT NULL,
+  black_row INTEGER NOT NULL,
+  black_col INTEGER NOT NULL,
+  result    BOOLEAN         ,
+  error     TEXT
+);
+
+.mode csv
+.import ./data.csv "queen-attack"
+
+UPDATE "queen-attack" SET result = NULL, error = NULL;

exercises/practice/queen-attack/create_test_table.sql

@@ -0,0 +1,44 @@
+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
+  white_row INTEGER NOT NULL,
+  white_col INTEGER NOT NULL,
+  black_row INTEGER NOT NULL,
+  black_col INTEGER NOT NULL,
+  expected_result BOOLEAN,
+  expected_error TEXT
+);
+
+INSERT INTO tests (
+  uuid           ,
+  description    ,
+  white_row      ,
+  white_col      ,
+  black_row      ,
+  black_col      ,
+  expected_result,
+  expected_error
+)
+VALUES
+('3ac4f735-d36c-44c4-a3e2-316f79704203', 'queen with a valid position', 2, 2, 2, 2, 1, NULL),
+('4e812d5d-b974-4e38-9a6b-8e0492bfa7be', 'queen must have positive row', -2, 2, -2, 2, NULL, 'row not positive'),
+('f07b7536-b66b-4f08-beb9-4d70d891d5c8', 'queen must have row on board', 8, 4, 8, 4, NULL, 'row not on board'),
+('15a10794-36d9-4907-ae6b-e5a0d4c54ebe', 'queen must have positive column', 2, -2, 2, -2, NULL, 'column not positive'),
+('6907762d-0e8a-4c38-87fb-12f2f65f0ce4', 'queen must have column on board', 4, 8, 4, 8, NULL, 'column not on board'),
+('33ae4113-d237-42ee-bac1-e1e699c0c007', 'cannot attack', 2, 4, 6, 6, 0, NULL),
+('eaa65540-ea7c-4152-8c21-003c7a68c914', 'can attack on same row', 2, 4, 2, 6, 1, NULL),
+('bae6f609-2c0e-4154-af71-af82b7c31cea', 'can attack on same column', 4, 5, 2, 5, 1, NULL),
+('0e1b4139-b90d-4562-bd58-dfa04f1746c7', 'can attack on first diagonal', 2, 2, 0, 4, 1, NULL),
+('ff9b7ed4-e4b6-401b-8d16-bc894d6d3dcd', 'can attack on second diagonal', 2, 2, 3, 1, 1, NULL),
+('0a71e605-6e28-4cc2-aa47-d20a2e71037a', 'can attack on third diagonal', 2, 2, 1, 1, 1, NULL),
+('0790b588-ae73-4f1f-a968-dd0b34f45f86', 'can attack on fourth diagonal', 1, 7, 0, 6, 1, NULL),
+('543f8fd4-2597-4aad-8d77-cbdab63619f8', 'cannot attack if falling diagonals are only the same when reflected across the longest falling diagonal', 4, 1, 2, 5, 0, NULL);

exercises/practice/queen-attack/data.csv

@@ -0,0 +1,13 @@
+2,2,2,2,,
+-2,2,-2,2,,
+8,4,8,4,,
+2,-2,2,-2,,
+4,8,4,8,,
+2,4,6,6,,
+2,4,2,6,,
+4,5,2,5,,
+2,2,0,4,,
+2,2,3,1,,
+2,2,1,1,,
+1,7,0,6,,
+4,1,2,5,,

exercises/practice/queen-attack/queen-attack.sql

@@ -0,0 +1,11 @@
+-- Schema:
+-- CREATE TABLE "queen-attack" (
+--   white_row INTEGER NOT NULL,
+--   white_col INTEGER NOT NULL,
+--   black_row INTEGER NOT NULL,
+--   black_col INTEGER NOT NULL,
+--   result    BOOLEAN         ,
+--   error     TEXT
+-- );
+--
+-- Task: update the "queen-attack" table and set the result or the error columns based on the white and black queens positions.

exercises/practice/queen-attack/queen-attack_test.sql

@@ -0,0 +1,69 @@
+-- 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 ./queen-attack.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 white_row, white_col, black_row, black_col, result, error
+          FROM "queen-attack") AS actual
+ WHERE (actual.white_row, actual.white_col, actual.black_row, actual.black_col)
+     = ( tests.white_row,  tests.white_col,  tests.black_row,  tests.black_col)
+   AND (actual.result = tests.expected_result
+        OR (actual.result ISNULL AND tests.expected_result ISNULL))
+   AND (actual.error = tests.expected_error
+        OR (actual.error ISNULL AND tests.expected_error ISNULL))
+;
+
+-- Update message for failed tests to give helpful information:
+UPDATE tests
+   SET message = (
+         'Result for "'
+         || PRINTF('white(row,col)=(%d,%d), black(row,col)=(%d,%d)',
+                   actual.white_row, actual.white_col,
+                   actual.black_row, actual.black_col)
+         || '"' || ' is <'
+         || PRINTF('result=%s and error=%s',
+                   COALESCE(actual.result, 'NULL'),
+                   COALESCE(actual.error,  'NULL'))
+         || '> but should be <'
+         || PRINTF('result=%s and error=%s',
+                   COALESCE(tests.expected_result, 'NULL'),
+                   COALESCE(tests.expected_error,  'NULL'))
+         || '>'
+  )
+  FROM (SELECT white_row, white_col, black_row, black_col, result, error
+          FROM "queen-attack") AS actual
+ WHERE (actual.white_row, actual.white_col, actual.black_row, actual.black_col)
+     = ( tests.white_row,  tests.white_col,  tests.black_row,  tests.black_col)
+   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;