feat: add Pascal's Triangle exercise (#74)

Author: Steffan153

config.json

@@ -201,6 +201,14 @@
         "practices": [],
         "prerequisites": [],
         "difficulty": 8
+      },
+      {
+        "slug": "pascals-triangle",
+        "name": "Pascal's Triangle",
+        "uuid": "fb614e0d-ad10-4710-8785-5ab07fd9eb5a",
+        "practices": [],
+        "prerequisites": [],
+        "difficulty": 8
       }
     ]
   },

exercises/practice/pascals-triangle/.docs/instructions.md

@@ -0,0 +1,14 @@
+# Instructions
+
+Compute Pascal's triangle up to a given number of rows.
+
+In Pascal's Triangle each number is computed by adding the numbers to the right and left of the current position in the previous row.
+
+```text
+    1
+   1 1
+  1 2 1
+ 1 3 3 1
+1 4 6 4 1
+# ... etc
+```

exercises/practice/pascals-triangle/.meta/config.json

@@ -0,0 +1,22 @@
+{
+  "authors": [
+    "Steffan153"
+  ],
+  "files": {
+    "solution": [
+      "pascals-triangle.sql"
+    ],
+    "test": [
+      "pascals-triangle_test.sql"
+    ],
+    "example": [
+      ".meta/example.sql"
+    ],
+    "editor": [
+      "data.csv"
+    ]
+  },
+  "blurb": "Compute Pascal's triangle up to a given number of rows.",
+  "source": "Pascal's Triangle at Wolfram Math World",
+  "source_url": "https://www.wolframalpha.com/input/?i=Pascal%27s+triangle"
+}

exercises/practice/pascals-triangle/.meta/example.sql

@@ -0,0 +1,23 @@
+UPDATE "pascals-triangle"
+SET result = (
+  WITH RECURSIVE counter(k) AS (
+    SELECT 1 UNION ALL
+    SELECT k + 1 FROM counter WHERE k < input
+  )
+
+  SELECT group_concat(
+    (
+      WITH RECURSIVE nums(idx, s) AS (
+        SELECT 1, 1 UNION ALL
+        SELECT idx + 1, s * k / idx - s FROM nums WHERE idx < k
+      )
+
+      SELECT group_concat(s, ' ') FROM nums
+    ),
+    char(10)  -- newline
+  ) FROM counter
+);
+
+UPDATE "pascals-triangle"
+SET result = ''
+WHERE input = 0;

exercises/practice/pascals-triangle/.meta/tests.toml

@@ -0,0 +1,34 @@
+# 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.
+
+[9920ce55-9629-46d5-85d6-4201f4a4234d]
+description = "zero rows"
+
+[70d643ce-a46d-4e93-af58-12d88dd01f21]
+description = "single row"
+
+[a6e5a2a2-fc9a-4b47-9f4f-ed9ad9fbe4bd]
+description = "two rows"
+
+[97206a99-79ba-4b04-b1c5-3c0fa1e16925]
+description = "three rows"
+
+[565a0431-c797-417c-a2c8-2935e01ce306]
+description = "four rows"
+
+[06f9ea50-9f51-4eb2-b9a9-c00975686c27]
+description = "five rows"
+
+[c3912965-ddb4-46a9-848e-3363e6b00b13]
+description = "six rows"
+
+[6cb26c66-7b57-4161-962c-81ec8c99f16b]
+description = "ten rows"

exercises/practice/pascals-triangle/create_fixture.sql

@@ -0,0 +1,8 @@
+DROP TABLE IF EXISTS "pascals-triangle";
+CREATE TABLE "pascals-triangle" (
+    "input" INT,
+    "result" TEXT
+);
+
+.mode csv
+.import ./data.csv pascals-triangle

exercises/practice/pascals-triangle/data.csv

@@ -0,0 +1,8 @@
+0,""
+1,""
+2,""
+3,""
+4,""
+5,""
+6,""
+10,""

exercises/practice/pascals-triangle/pascals-triangle.sql

@@ -0,0 +1,2 @@
+-- Schema: CREATE TABLE "pascals-triangle" ("input" INT, "result" TEXT);
+-- Task: update the pascals-triangle table and set the result based on the input field.

exercises/practice/pascals-triangle/pascals-triangle_test.sql

@@ -0,0 +1,48 @@
+-- Setup test table and read in student solution:
+.read ./test_setup.sql
+
+-- Test cases:
+INSERT INTO tests (name, uuid,
+                    input, expected)
+    VALUES
+        ('zero rows', '9920ce55-9629-46d5-85d6-4201f4a4234d', 0, ''),
+        ('single row', '70d643ce-a46d-4e93-af58-12d88dd01f21', 1, '1'),
+        ('two rows', 'a6e5a2a2-fc9a-4b47-9f4f-ed9ad9fbe4bd', 2, '1
+1 1'),
+        ('three rows', '97206a99-79ba-4b04-b1c5-3c0fa1e16925', 3, '1
+1 1
+1 2 1'),
+        ('four rows', '565a0431-c797-417c-a2c8-2935e01ce306', 4, '1
+1 1
+1 2 1
+1 3 3 1'),
+        ('five rows', '06f9ea50-9f51-4eb2-b9a9-c00975686c27', 5, '1
+1 1
+1 2 1
+1 3 3 1
+1 4 6 4 1'),
+        ('six rows', 'c3912965-ddb4-46a9-848e-3363e6b00b13', 6, '1
+1 1
+1 2 1
+1 3 3 1
+1 4 6 4 1
+1 5 10 10 5 1'),
+        ('ten rows', '6cb26c66-7b57-4161-962c-81ec8c99f16b', 10, '1
+1 1
+1 2 1
+1 3 3 1
+1 4 6 4 1
+1 5 10 10 5 1
+1 6 15 20 15 6 1
+1 7 21 35 35 21 7 1
+1 8 28 56 70 56 28 8 1
+1 9 36 84 126 126 84 36 9 1');
+
+-- Comparison of user input and the tests updates the status for each test:
+UPDATE tests
+SET status = 'pass'
+FROM (SELECT input, result FROM "pascals-triangle") AS actual
+WHERE (actual.input, actual.result) = (tests.input, tests.expected);
+
+-- Write results and debug info:
+.read ./test_reporter.sql

exercises/practice/pascals-triangle/test_reporter.sql

@@ -0,0 +1,16 @@
+-- Update message for failed tests to give helpful information:
+UPDATE tests
+SET message = 'Result for ' || actual.input || ' is: "' || actual.result || '", but should be: "' || tests.expected || '"'
+FROM (SELECT input, result FROM "pascals-triangle") AS actual
+WHERE actual.input = tests.input AND tests.status = 'fail';
+
+-- Save results to ./output.json (needed by the online test-runner)
+.mode json
+.once './output.json'
+SELECT name, status, message, output, test_code, task_id
+FROM tests;
+
+-- Display test results in readable form for the student:
+.mode table
+SELECT name, status, message
+FROM tests;