Add practice exercise: largest-series-product

config.json

@@ -362,6 +362,14 @@
         "prerequisites": [],
         "difficulty": 8
       },
+      {
+        "slug": "largest-series-product",
+        "name": "Largest Series Product",
+        "uuid": "66555259-8a28-428a-bca8-c0b06c889297",
+        "practices": [],
+        "prerequisites": [],
+        "difficulty": 8
+      },
       {
         "slug": "luhn",
         "name": "Luhn",
@@ -441,19 +449,19 @@
         "practices": [],
         "prerequisites": [],
         "difficulty": 8
-      },        
+      },
       {
-        "slug": "saddle-points",
-        "name": "Saddle Points",
-        "uuid": "d050e56b-9f86-416c-baa3-10a98f47b944",  
+        "slug": "run-length-encoding",
+        "name": "Run-Length Encoding",
+        "uuid": "065feae7-f6fc-46b9-a226-d3d9df9d192b",
         "practices": [],
         "prerequisites": [],
         "difficulty": 8
       },
       {
-        "slug": "run-length-encoding",
-        "name": "Run-Length Encoding",
-        "uuid": "065feae7-f6fc-46b9-a226-d3d9df9d192b",
+        "slug": "saddle-points",
+        "name": "Saddle Points",
+        "uuid": "d050e56b-9f86-416c-baa3-10a98f47b944",
         "practices": [],
         "prerequisites": [],
         "difficulty": 8

exercises/practice/largest-series-product/.docs/instructions.md

@@ -0,0 +1,26 @@
+# Instructions
+
+Your task is to look for patterns in the long sequence of digits in the encrypted signal.
+
+The technique you're going to use here is called the largest series product.
+
+Let's define a few terms, first.
+
+- **input**: the sequence of digits that you need to analyze
+- **series**: a sequence of adjacent digits (those that are next to each other) that is contained within the input
+- **span**: how many digits long each series is
+- **product**: what you get when you multiply numbers together
+
+Let's work through an example, with the input `"63915"`.
+
+- To form a series, take adjacent digits in the original input.
+- If you are working with a span of `3`, there will be three possible series:
+  - `"639"`
+  - `"391"`
+  - `"915"`
+- Then we need to calculate the product of each series:
+  - The product of the series `"639"` is 162 (`6 × 3 × 9 = 162`)
+  - The product of the series `"391"` is 27 (`3 × 9 × 1 = 27`)
+  - The product of the series `"915"` is 45 (`9 × 1 × 5 = 45`)
+- 162 is bigger than both 27 and 45, so the largest series product of `"63915"` is from the series `"639"`.
+  So the answer is **162**.

exercises/practice/largest-series-product/.docs/introduction.md

@@ -0,0 +1,5 @@
+# Introduction
+
+You work for a government agency that has intercepted a series of encrypted communication signals from a group of bank robbers.
+The signals contain a long sequence of digits.
+Your team needs to use various digital signal processing techniques to analyze the signals and identify any patterns that may indicate the planning of a heist.

exercises/practice/largest-series-product/.meta/config.json

@@ -0,0 +1,19 @@
+{
+  "authors": [
+    "jimmytty"
+  ],
+  "files": {
+    "solution": [
+      "largest-series-product.sql"
+    ],
+    "test": [
+      "largest-series-product_test.sql"
+    ],
+    "example": [
+      ".meta/example.sql"
+    ]
+  },
+  "blurb": "Given a string of digits, calculate the largest product for a contiguous substring of digits of length n.",
+  "source": "A variation on Problem 8 at Project Euler",
+  "source_url": "https://projecteuler.net/problem=8"
+}

exercises/practice/largest-series-product/.meta/example.sql

@@ -0,0 +1,46 @@
+UPDATE "largest-series-product"
+   SET error = 'span must not exceed string length'
+ WHERE LENGTH(digits) < span
+;
+UPDATE "largest-series-product"
+   SET error = 'digits input must only contain digits'
+ WHERE GLOB('*[^0-9]*', digits)
+;
+UPDATE "largest-series-product"
+   SET error = 'span must not be negative'
+ WHERE span < 0
+;
+
+UPDATE "largest-series-product"
+   SET result = 1
+ WHERE span = 0
+;
+
+UPDATE "largest-series-product"
+   SET result = (
+       WITH RECURSIVE split_series (string, serie, product) AS (
+         VALUES (digits, NULL, NULL)
+         UNION ALL
+         SELECT SUBSTR(string, 2),
+                SUBSTR(string, 1, span),
+                (WITH RECURSIVE split_digits (serie, digit) AS (
+                   VALUES (SUBSTR(string, 1, span), NULL)
+                   UNION ALL
+                   SELECT SUBSTR(serie, 2), SUBSTR(serie, 1, 1) * 1
+                     FROM split_digits
+                    WHERE serie <> ''
+                )
+                SELECT IIF(
+                         (SELECT 1 FROM split_digits WHERE digit = 0),
+                         0, EXP(SUM(LN(digit)))) AS product
+                 FROM split_digits
+                WHERE digit NOTNULL
+                )
+           FROM split_series
+          WHERE string <> ''
+      )
+      SELECT ROUND(MAX(product)) FROM split_series WHERE LENGTH(serie) = span
+      )
+ WHERE error  ISNULL
+   AND result ISNULL
+;

exercises/practice/largest-series-product/.meta/tests.toml

@@ -0,0 +1,70 @@
+# 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.
+
+[7c82f8b7-e347-48ee-8a22-f672323324d4]
+description = "finds the largest product if span equals length"
+
+[88523f65-21ba-4458-a76a-b4aaf6e4cb5e]
+description = "can find the largest product of 2 with numbers in order"
+
+[f1376b48-1157-419d-92c2-1d7e36a70b8a]
+description = "can find the largest product of 2"
+
+[46356a67-7e02-489e-8fea-321c2fa7b4a4]
+description = "can find the largest product of 3 with numbers in order"
+
+[a2dcb54b-2b8f-4993-92dd-5ce56dece64a]
+description = "can find the largest product of 3"
+
+[673210a3-33cd-4708-940b-c482d7a88f9d]
+description = "can find the largest product of 5 with numbers in order"
+
+[02acd5a6-3bbf-46df-8282-8b313a80a7c9]
+description = "can get the largest product of a big number"
+
+[76dcc407-21e9-424c-a98e-609f269622b5]
+description = "reports zero if the only digits are zero"
+
+[6ef0df9f-52d4-4a5d-b210-f6fae5f20e19]
+description = "reports zero if all spans include zero"
+
+[5d81aaf7-4f67-4125-bf33-11493cc7eab7]
+description = "rejects span longer than string length"
+include = false
+
+[0ae1ce53-d9ba-41bb-827f-2fceb64f058b]
+description = "rejects span longer than string length"
+reimplements = "5d81aaf7-4f67-4125-bf33-11493cc7eab7"
+
+[06bc8b90-0c51-4c54-ac22-3ec3893a079e]
+description = "reports 1 for empty string and empty product (0 span)"
+
+[3ec0d92e-f2e2-4090-a380-70afee02f4c0]
+description = "reports 1 for nonempty string and empty product (0 span)"
+
+[6d96c691-4374-4404-80ee-2ea8f3613dd4]
+description = "rejects empty string and nonzero span"
+include = false
+
+[6cf66098-a6af-4223-aab1-26aeeefc7402]
+description = "rejects empty string and nonzero span"
+reimplements = "6d96c691-4374-4404-80ee-2ea8f3613dd4"
+
+[7a38f2d6-3c35-45f6-8d6f-12e6e32d4d74]
+description = "rejects invalid character in digits"
+
+[5fe3c0e5-a945-49f2-b584-f0814b4dd1ef]
+description = "rejects negative span"
+include = false
+
+[c859f34a-9bfe-4897-9c2f-6d7f8598e7f0]
+description = "rejects negative span"
+reimplements = "5fe3c0e5-a945-49f2-b584-f0814b4dd1ef"

exercises/practice/largest-series-product/create_fixture.sql

@@ -0,0 +1,12 @@
+DROP TABLE IF EXISTS "largest-series-product";
+CREATE TABLE "largest-series-product" (
+  digits TEXT    NOT NULL,
+  span   INTEGER NOT NULL,
+  result INTEGER         ,
+  error  TEXT
+);
+
+.mode csv
+.import ./data.csv "largest-series-product"
+
+UPDATE "largest-series-product" SET result = NULL, error = NULL;

exercises/practice/largest-series-product/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
+  digits TEXT NOT NULL,
+  span INTEGER NOT NULL,
+  expected_result INTEGER,
+  expected_error TEXT
+);
+
+INSERT INTO tests (uuid, description, digits, span, expected_result, expected_error)
+VALUES
+('7c82f8b7-e347-48ee-8a22-f672323324d4', 'finds the largest product if span equals length', '29', 2, 18, NULL),
+('88523f65-21ba-4458-a76a-b4aaf6e4cb5e', 'can find the largest product of 2 with numbers in order', '0123456789', 2, 72, NULL),
+('f1376b48-1157-419d-92c2-1d7e36a70b8a', 'can find the largest product of 2', '576802143', 2, 48, NULL),
+('46356a67-7e02-489e-8fea-321c2fa7b4a4', 'can find the largest product of 3 with numbers in order', '0123456789', 3, 504, NULL),
+('a2dcb54b-2b8f-4993-92dd-5ce56dece64a', 'can find the largest product of 3', '1027839564', 3, 270, NULL),
+('673210a3-33cd-4708-940b-c482d7a88f9d', 'can find the largest product of 5 with numbers in order', '0123456789', 5, 15120, NULL),
+('02acd5a6-3bbf-46df-8282-8b313a80a7c9', 'can get the largest product of a big number', '73167176531330624919225119674426574742355349194934', 6, 23520, NULL),
+('76dcc407-21e9-424c-a98e-609f269622b5', 'reports zero if the only digits are zero', '0000', 2, 0, NULL),
+('6ef0df9f-52d4-4a5d-b210-f6fae5f20e19', 'reports zero if all spans include zero', '99099', 3, 0, NULL),
+('0ae1ce53-d9ba-41bb-827f-2fceb64f058b', 'rejects span longer than string length', '123', 4, NULL, 'span must not exceed string length'),
+('06bc8b90-0c51-4c54-ac22-3ec3893a079e', 'reports 1 for empty string and empty product (0 span)', '', 0, 1, NULL),
+('3ec0d92e-f2e2-4090-a380-70afee02f4c0', 'reports 1 for nonempty string and empty product (0 span)', '123', 0, 1, NULL),
+('6cf66098-a6af-4223-aab1-26aeeefc7402', 'rejects empty string and nonzero span', '', 1, NULL, 'span must not exceed string length'),
+('7a38f2d6-3c35-45f6-8d6f-12e6e32d4d74', 'rejects invalid character in digits', '1234a5', 2, NULL, 'digits input must only contain digits'),
+('c859f34a-9bfe-4897-9c2f-6d7f8598e7f0', 'rejects negative span', '12345', -1, NULL, 'span must not be negative');

exercises/practice/largest-series-product/data.csv

@@ -0,0 +1,15 @@
+"29",2,,
+"0123456789",2,,
+"576802143",2,,
+"0123456789",3,,
+"1027839564",3,,
+"0123456789",5,,
+"73167176531330624919225119674426574742355349194934",6,,
+"0000",2,,
+"99099",3,,
+"123",4,,
+"",0,,
+"123",0,,
+"",1,,
+"1234a5",2,,
+"12345",-1,,

exercises/practice/largest-series-product/largest-series-product.sql

@@ -0,0 +1,9 @@
+-- Schema:
+-- CREATE TABLE "largest-series-product" (
+--   digits TEXT    NOT NULL,
+--   span   INTEGER NOT NULL,
+--   result INTEGER         ,
+--   error  TEXT
+-- );
+--
+-- Task: update the largest-series-product table and set the result or the error columns bases on the digits and the span.

exercises/practice/largest-series-product/largest-series-product_test.sql

@@ -0,0 +1,53 @@
+-- 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 ./largest-series-product.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 digits, span, result, error
+          FROM "largest-series-product") AS actual
+ WHERE (actual.digits, actual.span) = (tests.digits, tests.span)
+   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('digits=%s and span=%s', actual.digits, actual.span)
+         || '" 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 digits, span, result, error
+          FROM "largest-series-product") AS actual
+ WHERE (actual.digits, actual.span) = (tests.digits, tests.span)
+   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;