Sync problem specs

exercises/practice/binary-search-tree/.docs/instructions.md

@@ -19,29 +19,52 @@ All data in the left subtree is less than or equal to the current node's data, a
 
 For example, if we had a node containing the data 4, and we added the data 2, our tree would look like this:
 
+![A graph with root node 4 and a single child node 2.](https://assets.exercism.org/images/exercises/binary-search-tree/tree-4-2.svg)
+
+```text
       4
      /
     2
+```
 
 If we then added 6, it would look like this:
 
+![A graph with root node 4 and two child nodes 2 and 6.](https://assets.exercism.org/images/exercises/binary-search-tree/tree-4-2-6.svg)
+
+```text
       4
      / \
     2   6
+```
 
 If we then added 3, it would look like this
 
+![A graph with root node 4, two child nodes 2 and 6, and a grandchild node 3.](https://assets.exercism.org/images/exercises/binary-search-tree/tree-4-2-6-3.svg)
+
+```text
        4
      /   \
     2     6
      \
       3
+```
 
 And if we then added 1, 5, and 7, it would look like this
 
+![A graph with root node 4, two child nodes 2 and 6, and four grandchild nodes 1, 3, 5 and 7.](https://assets.exercism.org/images/exercises/binary-search-tree/tree-4-2-6-1-3-5-7.svg)
+
+```text
           4
         /   \
        /     \
       2       6
      / \     / \
     1   3   5   7
+```
+
+## Credit
+
+The images were created by [habere-et-dispertire][habere-et-dispertire] using [PGF/TikZ][pgf-tikz] by Till Tantau.
+
+[habere-et-dispertire]: https://exercism.org/profiles/habere-et-dispertire
+[pgf-tikz]: https://en.wikipedia.org/wiki/PGF/TikZ

exercises/practice/eliuds-eggs/.docs/introduction.md

@@ -58,7 +58,7 @@ The position information encoding is calculated as follows:
 
 ### Decimal number on the display
 
-16
+8
 
 ### Actual eggs in the coop
 

exercises/practice/flatten-array/.docs/instructions.md

@@ -1,11 +1,16 @@
 # Instructions
 
-Take a nested list and return a single flattened list with all values except nil/null.
+Take a nested array of any depth and return a fully flattened array.
 
-The challenge is to take an arbitrarily-deep nested list-like structure and produce a flattened structure without any nil/null values.
+Note that some language tracks may include null-like values in the input array, and the way these values are represented varies by track.
+Such values should be excluded from the flattened array.
 
-For example:
+Additionally, the input may be of a different data type and contain different types, depending on the track.
 
-input: [1,[2,3,null,4],[null],5]
+Check the test suite for details.
 
-output: [1,2,3,4,5]
+## Example
+
+input: `[1, [2, 6, null], [[null, [4]], 5]]`
+
+output: `[1, 2, 6, 4, 5]`

exercises/practice/flatten-array/.docs/introduction.md

@@ -0,0 +1,7 @@
+# Introduction
+
+A shipment of emergency supplies has arrived, but there's a problem.
+To protect from damage, the items — flashlights, first-aid kits, blankets — are packed inside boxes, and some of those boxes are nested several layers deep inside other boxes!
+
+To be prepared for an emergency, everything must be easily accessible in one box.
+Can you unpack all the supplies and place them into a single box, so they're ready when needed most?

exercises/practice/flatten-array/.meta/tests.toml

@@ -32,12 +32,32 @@ description = "null values are omitted from the final result"
 
 [c6cf26de-8ccd-4410-84bd-b9efd88fd2bc]
 description = "consecutive null values at the front of the list are omitted from the final result"
+include = false
+
+[bc72da10-5f55-4ada-baf3-50e4da02ec8e]
+description = "consecutive null values at the front of the array are omitted from the final result"
+reimplements = "c6cf26de-8ccd-4410-84bd-b9efd88fd2bc"
 
 [382c5242-587e-4577-b8ce-a5fb51e385a1]
 description = "consecutive null values in the middle of the list are omitted from the final result"
+include = false
+
+[6991836d-0d9b-4703-80a0-3f1f23eb5981]
+description = "consecutive null values in the middle of the array are omitted from the final result"
+reimplements = "382c5242-587e-4577-b8ce-a5fb51e385a1"
 
 [ef1d4790-1b1e-4939-a179-51ace0829dbd]
 description = "6 level nest list with null values"
+include = false
+
+[dc90a09c-5376-449c-a7b3-c2d20d540069]
+description = "6 level nested array with null values"
+reimplements = "ef1d4790-1b1e-4939-a179-51ace0829dbd"
 
 [85721643-705a-4150-93ab-7ae398e2942d]
 description = "all values in nested list are null"
+include = false
+
+[51f5d9af-8f7f-4fb5-a156-69e8282cb275]
+description = "all values in nested array are null"
+reimplements = "85721643-705a-4150-93ab-7ae398e2942d"

exercises/practice/flatten-array/flatten-array.spec.coffee

@@ -31,22 +31,22 @@ describe 'Flatten Array', ->
     expected = [1, 2]
     expect(FlattenArray.flatten values).toEqual expected
 
-  xit 'consecutive null values at the front of the list are omitted from the final result', ->
+  xit 'consecutive null values at the front of the array are omitted from the final result', ->
     values = [null, null, 3]
     expected = [3]
     expect(FlattenArray.flatten values).toEqual expected
 
-  xit 'consecutive null values in the middle of the list are omitted from the final result', ->
+  xit 'consecutive null values in the middle of the array are omitted from the final result', ->
     values = [1, null, null, 4]
     expected = [1, 4]
     expect(FlattenArray.flatten values).toEqual expected
 
-  xit '6 level nest list with null values', ->
+  xit '6 level nest array with null values', ->
     values = [0, 2, [[2, 3], 8, [[100]], null, [[null]]], -2]
     expected = [0, 2, 2, 3, 8, 100, -2]
     expect(FlattenArray.flatten values).toEqual expected
 
-  xit 'all values in nested list are null', ->
+  xit 'all values in nested array are null', ->
     values = [null, [[[null]]], null, null, [[null, null], null], null]
     expected = []
     expect(FlattenArray.flatten values).toEqual expected

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

@@ -3,7 +3,7 @@ class LargestSeriesProduct
     if span < 0
       throw new Error 'span must not be negative'
     if span > digits.length
-      throw new Error 'span must be smaller than string length'
+      throw new Error 'span must not exceed string length'
     if digits.match(/[^0-9]/)
       throw new Error 'digits input must only contain digits'
 

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

@@ -38,6 +38,11 @@ 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)"
@@ -47,6 +52,11 @@ 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"

exercises/practice/largest-series-product/largest-series-product.spec.coffee

@@ -40,7 +40,7 @@ describe 'Largest Series Product', ->
   xit 'rejects span longer than string length', ->
     expect ->
       Lsp.largestProduct '123', 4
-    .toThrow new Error 'span must be smaller than string length'
+    .toThrow new Error 'span must not exceed string length'
 
   xit 'reports 1 for empty string and empty product (0 span)', ->
     result = Lsp.largestProduct '', 0
@@ -53,7 +53,7 @@ describe 'Largest Series Product', ->
   xit 'rejects empty string and nonzero span', ->
     expect ->
       Lsp.largestProduct '', 1
-    .toThrow new Error 'span must be smaller than string length'
+    .toThrow new Error 'span must not exceed string length'
 
   xit 'rejects invalid character in digits', ->
     expect ->

exercises/practice/luhn/.docs/instructions.md

@@ -1,6 +1,6 @@
 # Instructions
 
-Determine whether a credit card number is valid according to the [Luhn formula][luhn].
+Determine whether a number is valid according to the [Luhn formula][luhn].
 
 The number will be provided as a string.
 
@@ -10,54 +10,59 @@ Strings of length 1 or less are not valid.
 Spaces are allowed in the input, but they should be stripped before checking.
 All other non-digit characters are disallowed.
 
-### Example 1: valid credit card number
+## Examples
 
-```text
-4539 3195 0343 6467
-```
+### Valid credit card number
 
-The first step of the Luhn algorithm is to double every second digit, starting from the right.
-We will be doubling
+The number to be checked is `4539 3195 0343 6467`.
+
+The first step of the Luhn algorithm is to start at the end of the number and double every second digit, beginning with the second digit from the right and moving left.
 
 ```text
 4539 3195 0343 6467
 ↑ ↑  ↑ ↑  ↑ ↑  ↑ ↑  (double these)
 ```
 
-If doubling the number results in a number greater than 9 then subtract 9 from the product.
-The results of our doubling:
+If the result of doubling a digit is greater than 9, we subtract 9 from that result.
+We end up with:
 
 ```text
 8569 6195 0383 3437
 ```
 
-Then sum all of the digits:
+Finally, we sum all digits.
+If the sum is evenly divisible by 10, the original number is valid.
 
 ```text
-8+5+6+9+6+1+9+5+0+3+8+3+3+4+3+7 = 80
+8 + 5 + 6 + 9 + 6 + 1 + 9 + 5 + 0 + 3 + 8 + 3 + 3 + 4 + 3 + 7 = 80
 ```
 
-If the sum is evenly divisible by 10, then the number is valid.
-This number is valid!
+80 is evenly divisible by 10, so number `4539 3195 0343 6467` is valid!
+
+### Invalid Canadian SIN
+
+The number to be checked is `066 123 468`.
 
-### Example 2: invalid credit card number
+We start at the end of the number and double every second digit, beginning with the second digit from the right and moving left.
 
 ```text
-8273 1232 7352 0569
+066 123 478
+ ↑  ↑ ↑  ↑  (double these)
 ```
 
-Double the second digits, starting from the right
+If the result of doubling a digit is greater than 9, we subtract 9 from that result.
+We end up with:
 
 ```text
-7253 2262 5312 0539
+036 226 458
 ```
 
-Sum the digits
+We sum the digits:
 
 ```text
-7+2+5+3+2+2+6+2+5+3+1+2+0+5+3+9 = 57
+0 + 3 + 6 + 2 + 2 + 6 + 4 + 5 + 8 = 36
 ```
 
-57 is not evenly divisible by 10, so this number is not valid.
+36 is not evenly divisible by 10, so number `066 123 478` is not valid!
 
 [luhn]: https://en.wikipedia.org/wiki/Luhn_algorithm

exercises/practice/luhn/.docs/introduction.md

@@ -2,10 +2,10 @@
 
 At the Global Verification Authority, you've just been entrusted with a critical assignment.
 Across the city, from online purchases to secure logins, countless operations rely on the accuracy of numerical identifiers like credit card numbers, bank account numbers, transaction codes, and tracking IDs.
-The Luhn algorithm is a simple checksum formula used to ensure these numbers are valid and error-free.
+The Luhn algorithm is a simple checksum formula used to help identify mistyped numbers.
 
 A batch of identifiers has just arrived on your desk.
 All of them must pass the Luhn test to ensure they're legitimate.
-If any fail, they'll be flagged as invalid, preventing errors or fraud, such as incorrect transactions or unauthorized access.
+If any fail, they'll be flagged as invalid, preventing mistakes such as incorrect transactions or failed account verifications.
 
 Can you ensure this is done right? The integrity of many services depends on you.

exercises/practice/meetup/.docs/instructions.md

@@ -2,7 +2,7 @@
 
 Your task is to find the exact date of a meetup, given a month, year, weekday and week.
 
-There are five week values to consider: `first`, `second`, `third`, `fourth`, `last`, `teenth`.
+There are six week values to consider: `first`, `second`, `third`, `fourth`, `last`, `teenth`.
 
 For example, you might be asked to find the date for the meetup on the first Monday in January 2018 (January 1, 2018).
 

exercises/practice/phone-number/.docs/instructions.md

@@ -1,6 +1,6 @@
 # Instructions
 
-Clean up user-entered phone numbers so that they can be sent SMS messages.
+Clean up phone numbers so that they can be sent SMS messages.
 
 The **North American Numbering Plan (NANP)** is a telephone numbering system used by many countries in North America like the United States, Canada or Bermuda.
 All NANP-countries share the same international country code: `1`.

exercises/practice/relative-distance/.docs/instructions.md

@@ -1,6 +1,7 @@
 # Instructions
 
 Your task is to determine the degree of separation between two individuals in a family tree.
+This is similar to the pop culture idea that every Hollywood actor is [within six degrees of Kevin Bacon][six-bacons].
 
 - You will be given an input, with all parent names and their children.
 - Each name is unique, a child _can_ have one or two parents.
@@ -13,22 +14,21 @@ Your task is to determine the degree of separation between two individuals in a
 Given the following family tree:
 
 ```text
-      ┌──────────┐            ┌──────────┐ ┌───────────┐
-      │  Helena  │            │  Erdős   │ │  Shusaku  │
-      └───┬───┬──┘            └─────┬────┘ └──────┬────┘
-      ┌───┘   └───────┐             └──────┬──────┘
-      ▼               ▼                    ▼
-┌──────────┐     ┌────────┐          ┌──────────┐
-│   Isla   │     │  Tariq │          │   Kevin  │
-└────┬─────┘     └────┬───┘          └──────────┘
-     ▼                ▼
-┌─────────┐      ┌────────┐
+      ┌──────────┐            ┌──────────┐     ┌───────────┐
+      │  Helena  │            │  Erdős   ├─────┤  Shusaku  │
+      └───┬───┬──┘            └─────┬────┘     └────┬──────┘
+      ┌───┘   └───────┐             └───────┬───────┘
+┌─────┴────┐     ┌────┴───┐           ┌─────┴────┐
+│   Isla   ├─────┤ Tariq  │           │   Kevin  │
+└────┬─────┘     └────┬───┘           └──────────┘
+     │                │
+┌────┴────┐      ┌────┴───┐
 │   Uma   │      │ Morphy │
 └─────────┘      └────────┘
 ```
 
-The degree of separation between Tariq and Uma is 3 (Tariq → Helena → Isla → Uma).
-There's no known relationship between Isla and [Kevin][six-bacons], as there is no connection in the given data.
+The degree of separation between Tariq and Uma is 2 (Tariq → Isla → Uma).
+There's no known relationship between Isla and Kevin, as there is no connection in the given data.
 The degree of separation between Uma and Isla is 1.
 
 ~~~~exercism/note