Add new practice exercise resistor-color-trio (#100)

Author: jimmytty

config.json

@@ -178,6 +178,14 @@
         "prerequisites": [],
         "difficulty": 5
       },
+      {
+        "slug": "resistor-color-trio",
+        "name": "Resistor Color Trio",
+        "uuid": "ff9d1780-bc8c-49d6-9c33-dba769d551fb",
+        "practices": [],
+        "prerequisites": [],
+        "difficulty": 5
+      },
       {
         "slug": "rest-api",
         "name": "REST API",

exercises/practice/resistor-color-trio/.docs/instructions.md

@@ -0,0 +1,56 @@
+# Instructions
+
+If you want to build something using a Raspberry Pi, you'll probably use _resistors_.
+For this exercise, you need to know only three things about them:
+
+- Each resistor has a resistance value.
+- Resistors are small - so small in fact that if you printed the resistance value on them, it would be hard to read.
+  To get around this problem, manufacturers print color-coded bands onto the resistors to denote their resistance values.
+- Each band acts as a digit of a number.
+  For example, if they printed a brown band (value 1) followed by a green band (value 5), it would translate to the number 15.
+  In this exercise, you are going to create a helpful program so that you don't have to remember the values of the bands.
+  The program will take 3 colors as input, and outputs the correct value, in ohms.
+  The color bands are encoded as follows:
+
+- black: 0
+- brown: 1
+- red: 2
+- orange: 3
+- yellow: 4
+- green: 5
+- blue: 6
+- violet: 7
+- grey: 8
+- white: 9
+
+In Resistor Color Duo you decoded the first two colors.
+For instance: orange-orange got the main value `33`.
+The third color stands for how many zeros need to be added to the main value.
+The main value plus the zeros gives us a value in ohms.
+For the exercise it doesn't matter what ohms really are.
+For example:
+
+- orange-orange-black would be 33 and no zeros, which becomes 33 ohms.
+- orange-orange-red would be 33 and 2 zeros, which becomes 3300 ohms.
+- orange-orange-orange would be 33 and 3 zeros, which becomes 33000 ohms.
+
+(If Math is your thing, you may want to think of the zeros as exponents of 10.
+If Math is not your thing, go with the zeros.
+It really is the same thing, just in plain English instead of Math lingo.)
+
+This exercise is about translating the colors into a label:
+
+> "... ohms"
+
+So an input of `"orange", "orange", "black"` should return:
+
+> "33 ohms"
+
+When we get to larger resistors, a [metric prefix][metric-prefix] is used to indicate a larger magnitude of ohms, such as "kiloohms".
+That is similar to saying "2 kilometers" instead of "2000 meters", or "2 kilograms" for "2000 grams".
+
+For example, an input of `"orange", "orange", "orange"` should return:
+
+> "33 kiloohms"
+
+[metric-prefix]: https://en.wikipedia.org/wiki/Metric_prefix

exercises/practice/resistor-color-trio/.meta/config.json

@@ -0,0 +1,19 @@
+{
+  "authors": [
+    "jimmytty"
+  ],
+  "files": {
+    "solution": [
+      "resistor-color-trio.sql"
+    ],
+    "test": [
+      "resistor-color-trio_test.sql"
+    ],
+    "example": [
+      ".meta/example.sql"
+    ]
+  },
+  "blurb": "Convert color codes, as used on resistors, to a human-readable label.",
+  "source": "Maud de Vries, Erik Schierboom",
+  "source_url": "https://github.com/exercism/problem-specifications/issues/1549"
+}

exercises/practice/resistor-color-trio/.meta/example.sql

@@ -0,0 +1,37 @@
+DROP TABLE IF EXISTS dict;
+CREATE TABLE dict (
+  code  INTEGER,
+  color TEXT
+);
+INSERT INTO dict (code, color)
+VALUES
+(0, 'black'  ),
+(1, 'brown'  ),
+(2, 'red'    ),
+(3, 'orange' ),
+(4, 'yellow' ),
+(5, 'green'  ),
+(6, 'blue'   ),
+(7, 'violet' ),
+(8, 'grey'   ),
+(9, 'white'  );
+
+UPDATE color_code
+   SET result = (
+     WITH value AS (
+       SELECT (
+         (SELECT code FROM dict WHERE color = color1) * 10
+         + (SELECT code FROM dict WHERE color = color2))
+         * POW(10, (SELECT code FROM dict WHERE color = color3))
+       AS v
+     )
+     SELECT
+       CASE
+       WHEN v >= 1e9 THEN CAST(v / 1e9 AS INTEGER) || ' gigaohms'
+       WHEN v >= 1e6 THEN CAST(v / 1e6 AS INTEGER) || ' megaohms'
+       WHEN v >= 1e3 THEN CAST(v / 1e3 AS INTEGER) || ' kiloohms'
+       ELSE CAST(v AS INTEGER) || ' ohms'
+       END
+       FROM value
+   )
+;

exercises/practice/resistor-color-trio/.meta/tests.toml

@@ -0,0 +1,41 @@
+# 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.
+
+[d6863355-15b7-40bb-abe0-bfb1a25512ed]
+description = "Orange and orange and black"
+
+[1224a3a9-8c8e-4032-843a-5224e04647d6]
+description = "Blue and grey and brown"
+
+[b8bda7dc-6b95-4539-abb2-2ad51d66a207]
+description = "Red and black and red"
+
+[5b1e74bc-d838-4eda-bbb3-eaba988e733b]
+description = "Green and brown and orange"
+
+[f5d37ef9-1919-4719-a90d-a33c5a6934c9]
+description = "Yellow and violet and yellow"
+
+[5f6404a7-5bb3-4283-877d-3d39bcc33854]
+description = "Blue and violet and blue"
+
+[7d3a6ab8-e40e-46c3-98b1-91639fff2344]
+description = "Minimum possible value"
+
+[ca0aa0ac-3825-42de-9f07-dac68cc580fd]
+description = "Maximum possible value"
+
+[0061a76c-903a-4714-8ce2-f26ce23b0e09]
+description = "First two colors make an invalid octal number"
+
+[30872c92-f567-4b69-a105-8455611c10c4]
+description = "Ignore extra colors"
+include = false

exercises/practice/resistor-color-trio/create_fixture.sql

@@ -0,0 +1,10 @@
+-- The color_code has specific colors and needs the result filled in.
+DROP TABLE IF EXISTS color_code;
+CREATE TABLE color_code (
+  color1 TEXT,
+  color2 TEXT,
+  color3 TEXT,
+  result TEXT
+);
+.mode csv
+.import ./data.csv color_code

exercises/practice/resistor-color-trio/create_test_table.sql

@@ -0,0 +1,29 @@
+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
+    color1 TEXT NOT NULL,
+    color2 TEXT NOT NULL,
+    color3 TEXT NOT NULL,
+    expected TEXT NOT NULL
+);
+
+INSERT INTO tests (uuid, description, color1, color2, color3, expected)
+    VALUES
+        ('d6863355-15b7-40bb-abe0-bfb1a25512ed','Orange and orange and black','orange','orange','black','33 ohms'),
+        ('1224a3a9-8c8e-4032-843a-5224e04647d6','Blue and grey and brown','blue','grey','brown','680 ohms'),
+        ('b8bda7dc-6b95-4539-abb2-2ad51d66a207','Red and black and red','red','black','red','2 kiloohms'),
+        ('5b1e74bc-d838-4eda-bbb3-eaba988e733b','Green and brown and orange','green','brown','orange','51 kiloohms'),
+        ('f5d37ef9-1919-4719-a90d-a33c5a6934c9','Yellow and violet and yellow','yellow','violet','yellow','470 kiloohms'),
+        ('5f6404a7-5bb3-4283-877d-3d39bcc33854','Blue and violet and blue','blue','violet','blue','67 megaohms'),
+        ('7d3a6ab8-e40e-46c3-98b1-91639fff2344','Minimum possible value','black','black','black','0 ohms'),
+        ('ca0aa0ac-3825-42de-9f07-dac68cc580fd','Maximum possible value','white','white','white','99 gigaohms'),
+        ('0061a76c-903a-4714-8ce2-f26ce23b0e09','First two colors make an invalid octal number','black','grey','black','8 ohms');

exercises/practice/resistor-color-trio/data.csv

@@ -0,0 +1,9 @@
+"orange","orange","black",""
+"blue","grey","brown",""
+"red","black","red",""
+"green","brown","orange",""
+"yellow","violet","yellow",""
+"blue","violet","blue",""
+"black","black","black",""
+"white","white","white",""
+"black","grey","black",""

exercises/practice/resistor-color-trio/resistor-color-trio.sql

@@ -0,0 +1,2 @@
+-- Schema: CREATE TABLE IF NOT EXISTS color_code ( color1 TEXT, color2 TEXT, color3 TEXT, result TEXT );
+-- Task: update the color_code table and set the result based on the colors.

exercises/practice/resistor-color-trio/resistor-color-trio_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 ./resistor-color-trio.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 color1, color2, color3, result FROM color_code) AS actual
+WHERE (actual.color1, actual.color2, actual.color3, actual.result) = (tests.color1, tests.color2, tests.color3, tests.expected);
+
+-- Update message for failed tests to give helpful information:
+UPDATE tests
+SET message = (
+    'Result for "'
+    || tests.color1 || ',' || tests.color2 || ',' || tests.color3
+    || '"'
+    || ' is <' || COALESCE(actual.result, 'NULL')
+    || '> but should be <' || tests.expected || '>'
+)
+FROM (SELECT color1, color2, color3, result FROM color_code) AS actual
+WHERE (actual.color1, actual.color2, actual.color3) = (tests.color1, tests.color2, tests.color3) 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;