Sync docs and a couple of tests (#2820)

exercises/practice/affine-cipher/.docs/instructions.md

@@ -18,10 +18,10 @@ E(x) = (ai + b) mod m
 
 Where:
 
-- `i` is the letter's index from `0` to the length of the alphabet - 1
+- `i` is the letter's index from `0` to the length of the alphabet - 1.
 - `m` is the length of the alphabet.
   For the Roman alphabet `m` is `26`.
-- `a` and `b` are integers which make the encryption key
+- `a` and `b` are integers which make up the encryption key.
 
 Values `a` and `m` must be _coprime_ (or, _relatively prime_) for automatic decryption to succeed, i.e., they have number `1` as their only common factor (more information can be found in the [Wikipedia article about coprime integers][coprime-integers]).
 In case `a` is not coprime to `m`, your program should indicate that this is an error.

exercises/practice/bank-account/.docs/instructions.md

@@ -3,7 +3,7 @@
 Your task is to implement bank accounts supporting opening/closing, withdrawals, and deposits of money.
 
 As bank accounts can be accessed in many different ways (internet, mobile phones, automatic charges), your bank software must allow accounts to be safely accessed from multiple threads/processes (terminology depends on your programming language) in parallel.
-For example, there may be many deposits and withdrawals occurring in parallel; you need to ensure there is no [race conditions][wikipedia] between when you read the account balance and set the new balance.
+For example, there may be many deposits and withdrawals occurring in parallel; you need to ensure there are no [race conditions][wikipedia] between when you read the account balance and set the new balance.
 
 It should be possible to close an account; operations against a closed account must fail.
 

exercises/practice/change/.meta/tests.toml

@@ -33,6 +33,9 @@ description = "possible change without unit coins available"
 [9a166411-d35d-4f7f-a007-6724ac266178]
 description = "another possible change without unit coins available"
 
+[ce0f80d5-51c3-469d-818c-3e69dbd25f75]
+description = "a greedy approach is not optimal"
+
 [bbbcc154-e9e9-4209-a4db-dd6d81ec26bb]
 description = "no coins make 0 change"
 

exercises/practice/change/src/test/java/ChangeCalculatorTest.java

@@ -35,7 +35,6 @@ public void testChangeThatMustBeGivenInMultipleCoins() {
 
     @Disabled("Remove to run test")
     @Test
-    // https://en.wikipedia.org/wiki/Change-making_problem#Greedy_method
     public void testLilliputianCurrency() {
         ChangeCalculator changeCalculator = new ChangeCalculator(asList(1, 4, 15, 20, 50));
 
@@ -45,7 +44,6 @@ public void testLilliputianCurrency() {
 
     @Disabled("Remove to run test")
     @Test
-    // https://en.wikipedia.org/wiki/Change-making_problem#Greedy_method
     public void testLowerElbonianCurrency() {
         ChangeCalculator changeCalculator = new ChangeCalculator(asList(1, 5, 10, 21, 25));
 
@@ -64,7 +62,6 @@ public void testLargeAmountOfChange() {
 
     @Disabled("Remove to run test")
     @Test
-    // https://en.wikipedia.org/wiki/Change-making_problem#Greedy_method
     public void testPossibleChangeWithoutUnitCoinAvailable() {
         ChangeCalculator changeCalculator = new ChangeCalculator(asList(2, 5, 10, 20, 50));
 
@@ -74,14 +71,22 @@ public void testPossibleChangeWithoutUnitCoinAvailable() {
 
     @Disabled("Remove to run test")
     @Test
-    // https://en.wikipedia.org/wiki/Change-making_problem#Greedy_method
     public void testAnotherPossibleChangeWithoutUnitCoinAvailable() {
         ChangeCalculator changeCalculator = new ChangeCalculator(asList(4, 5));
 
         assertThat(changeCalculator.computeMostEfficientChange(27))
             .containsExactly(4, 4, 4, 5, 5, 5);
     }
 
+    @Disabled("Remove to run test")
+    @Test
+    public void testAGreedyApproachIsNotOptimal() {
+        ChangeCalculator changeCalculator = new ChangeCalculator(asList(1, 10, 11));
+
+        assertThat(changeCalculator.computeMostEfficientChange(20))
+            .containsExactly(10, 10);
+    }
+
     @Disabled("Remove to run test")
     @Test
     public void testZeroChange() {

exercises/practice/custom-set/.meta/tests.toml

@@ -114,6 +114,9 @@ description = "Difference (or Complement) of a set is a set of all elements that
 [c5ac673e-d707-4db5-8d69-7082c3a5437e]
 description = "Difference (or Complement) of a set is a set of all elements that are only in the first set -> difference of two non-empty sets is a set of elements that are only in the first set"
 
+[20d0a38f-7bb7-4c4a-ac15-90c7392ecf2b]
+description = "Difference (or Complement) of a set is a set of all elements that are only in the first set -> difference removes all duplicates in the first set"
+
 [c45aed16-5494-455a-9033-5d4c93589dc6]
 description = "Union returns a set of all elements in either set -> union of empty sets is an empty set"
 

exercises/practice/custom-set/src/test/java/CustomSetTest.java

@@ -180,12 +180,20 @@ public void setIsNotEqualToLargerSetWithSameElements() {
 
     @Disabled("Remove to run test")
     @Test
-    public void setIsEqualToSetConstructedFromListWithDuplicates() {
+    public void secondSetWithDuplicatesIsEqualToFirstSet() {
         CustomSet<String> customSet = new CustomSet<>(Collections.singletonList("1"));
         CustomSet<String> secondCustomSet = new CustomSet<>(Arrays.asList("1", "1"));
         assertThat(customSet.equals(secondCustomSet)).isTrue();
     }
 
+    @Disabled("Remove to run test")
+    @Test
+    public void firstSetWithDuplicatesIsEqualToSecondSet() {
+        CustomSet<String> customSet = new CustomSet<>(Arrays.asList("1", "1"));
+        CustomSet<String> secondCustomSet = new CustomSet<>(Collections.singletonList("1"));
+        assertThat(customSet.equals(secondCustomSet)).isTrue();
+    }
+
     @Disabled("Remove to run test")
     @Test
     public void addToEmptySet() {

exercises/practice/go-counting/.docs/instructions.md

@@ -25,7 +25,7 @@ Empty spaces represent empty intersections.
 
 To be more precise an empty intersection is part of a player's territory if all of its neighbors are either stones of that player or empty intersections that are part of that player's territory.
 
-For more information see [wikipedia][go-wikipedia] or [Sensei's Library][go-sensei].
+For more information see [Wikipedia][go-wikipedia] or [Sensei's Library][go-sensei].
 
 [go-wikipedia]: https://en.wikipedia.org/wiki/Go_%28game%29
 [go-sensei]: https://senseis.xmp.net/

exercises/practice/killer-sudoku-helper/.docs/instructions.md

@@ -20,7 +20,17 @@ In a 3-digit cage with a sum of 7, there is only one valid combination: 124.
 - 1 + 2 + 4 = 7
 - Any other combination that adds up to 7, e.g. 232, would violate the rule of not repeating digits within a cage.
 
-![Sudoku grid, with three killer cages that are marked as grouped together. The first killer cage is in the 3×3 box in the top left corner of the grid. The middle column of that box forms the cage, with the followings cells from top to bottom: first cell contains a 1 and a pencil mark of 7, indicating a cage sum of 7, second cell contains a 2, third cell contains a 5. The numbers are highlighted in red to indicate a mistake. The second killer cage is in the central 3×3 box of the grid. The middle column of that box forms the cage, with the followings cells from top to bottom: first cell contains a 1 and a pencil mark of 7, indicating a cage sum of 7, second cell contains a 2, third cell contains a 4. None of the numbers in this cage are highlighted and therefore don't contain any mistakes. The third killer cage follows the outside corner of the central 3×3 box of the grid. It is made up of the following three cells: the top left cell of the cage contains a 2, highlighted in red, and a cage sum of 7. The top right cell of the cage contains a 3. The bottom right cell of the cage contains a 2, highlighted in red. All other cells are empty.][one-solution-img]
+![Sudoku grid, with three killer cages that are marked as grouped together.
+The first killer cage is in the 3×3 box in the top left corner of the grid.
+The middle column of that box forms the cage, with the followings cells from top to bottom: first cell contains a 1 and a pencil mark of 7, indicating a cage sum of 7, second cell contains a 2, third cell contains a 5.
+The numbers are highlighted in red to indicate a mistake.
+The second killer cage is in the central 3×3 box of the grid.
+The middle column of that box forms the cage, with the followings cells from top to bottom: first cell contains a 1 and a pencil mark of 7, indicating a cage sum of 7, second cell contains a 2, third cell contains a 4.
+None of the numbers in this cage are highlighted and therefore don't contain any mistakes.
+The third killer cage follows the outside corner of the central 3×3 box of the grid.
+It is made up of the following three cells: the top left cell of the cage contains a 2, highlighted in red, and a cage sum of 7.
+The top right cell of the cage contains a 3.
+The bottom right cell of the cage contains a 2, highlighted in red. All other cells are empty.][one-solution-img]
 
 ## Example 2: Cage with several combinations
 
@@ -31,7 +41,13 @@ In a 2-digit cage with a sum 10, there are 4 possible combinations:
 - 37
 - 46
 
-![Sudoku grid, all squares empty except for the middle column, column 5, which has 8 rows filled. Each continguous two rows form a killer cage and are marked as grouped together. From top to bottom: first group is a cell with value 1 and a pencil mark indicating a cage sum of 10, cell with value 9. Second group is a cell with value 2 and a pencil mark of 10, cell with value 8. Third group is a cell with value 3 and a pencil mark of 10, cell with value 7. Fourth group is a cell with value 4 and a pencil mark of 10, cell with value 6. The last cell in the column is empty.][four-solutions-img]
+![Sudoku grid, all squares empty except for the middle column, column 5, which has 8 rows filled.
+Each continguous two rows form a killer cage and are marked as grouped together.
+From top to bottom: first group is a cell with value 1 and a pencil mark indicating a cage sum of 10, cell with value 9.
+Second group is a cell with value 2 and a pencil mark of 10, cell with value 8.
+Third group is a cell with value 3 and a pencil mark of 10, cell with value 7.
+Fourth group is a cell with value 4 and a pencil mark of 10, cell with value 6.
+The last cell in the column is empty.][four-solutions-img]
 
 ## Example 3: Cage with several combinations that is restricted
 
@@ -42,7 +58,13 @@ In a 2-digit cage with a sum 10, where the column already contains a 1 and a 4,
 
 19 and 46 are not possible due to the 1 and 4 in the column according to standard Sudoku rules.
 
-![Sudoku grid, all squares empty except for the middle column, column 5, which has 8 rows filled. The first row contains a 4, the second is empty, and the third contains a 1. The 1 is highlighted in red to indicate a mistake. The last 6 rows in the column form killer cages of two cells each. From top to bottom: first group is a cell with value 2 and a pencil mark indicating a cage sum of 10, cell with value 8. Second group is a cell with value 3 and a pencil mark of 10, cell with value 7. Third group is a cell with value 1, highlighted in red, and a pencil mark of 10, cell with value 9.][not-possible-img]
+![Sudoku grid, all squares empty except for the middle column, column 5, which has 8 rows filled.
+The first row contains a 4, the second is empty, and the third contains a 1.
+The 1 is highlighted in red to indicate a mistake.
+The last 6 rows in the column form killer cages of two cells each.
+From top to bottom: first group is a cell with value 2 and a pencil mark indicating a cage sum of 10, cell with value 8.
+Second group is a cell with value 3 and a pencil mark of 10, cell with value 7.
+Third group is a cell with value 1, highlighted in red, and a pencil mark of 10, cell with value 9.][not-possible-img]
 
 ## Trying it yourself
 

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

@@ -1,14 +1,35 @@
 # Instructions
 
-Compute Pascal's triangle up to a given number of rows.
+Your task is to output the first N rows of Pascal's triangle.
 
-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.
+[Pascal's triangle][wikipedia] is a triangular array of positive integers.
+
+In Pascal's triangle, the number of values in a row is equal to its row number (which starts at one).
+Therefore, the first row has one value, the second row has two values, and so on.
+
+The first (topmost) row has a single value: `1`.
+Subsequent rows' values are computed by adding the numbers directly to the right and left of the current position in the previous row.
+
+If the previous row does _not_ have a value to the left or right of the current position (which only happens for the leftmost and rightmost positions), treat that position's value as zero (effectively "ignoring" it in the summation).
+
+## Example
+
+Let's look at the first 5 rows of Pascal's Triangle:
 
 ```text
     1
    1 1
   1 2 1
  1 3 3 1
 1 4 6 4 1
-# ... etc
 ```
+
+The topmost row has one value, which is `1`.
+
+The leftmost and rightmost values have only one preceding position to consider, which is the position to its right respectively to its left.
+With the topmost value being `1`, it follows from this that all the leftmost and rightmost values are also `1`.
+
+The other values all have two positions to consider.
+For example, the fifth row's (`1 4 6 4 1`) middle value is `6`, as the values to its left and right in the preceding row are `3` and `3`:
+
+[wikipedia]: https://en.wikipedia.org/wiki/Pascal%27s_triangle

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

@@ -0,0 +1,22 @@
+# Introduction
+
+With the weather being great, you're not looking forward to spending an hour in a classroom.
+Annoyed, you enter the class room, where you notice a strangely satisfying triangle shape on the blackboard.
+Whilst waiting for your math teacher to arrive, you can't help but notice some patterns in the triangle: the outer values are all ones, each subsequent row has one more value than its previous row and the triangle is symmetrical.
+Weird!
+
+Not long after you sit down, your teacher enters the room and explains that this triangle is the famous [Pascal's triangle][wikipedia].
+
+Over the next hour, your teacher reveals some amazing things hidden in this triangle:
+
+- It can be used to compute how many ways you can pick K elements from N values.
+- It contains the Fibonacci sequence.
+- If you color odd and even numbers differently, you get a beautiful pattern called the [Sierpiński triangle][wikipedia-sierpinski-triangle].
+
+The teacher implores you and your classmates to lookup other uses, and assures you that there are lots more!
+At that moment, the school bell rings.
+You realize that for the past hour, you were completely absorbed in learning about Pascal's triangle.
+You quickly grab your laptop from your bag and go outside, ready to enjoy both the sunshine _and_ the wonders of Pascal's triangle.
+
+[wikipedia]: https://en.wikipedia.org/wiki/Pascal%27s_triangle
+[wikipedia-sierpinski-triangle]: https://en.wikipedia.org/wiki/Sierpi%C5%84ski_triangle

exercises/practice/pig-latin/.docs/instructions.md

@@ -19,7 +19,7 @@ For example:
 
 ## Rule 2
 
-If a word begins with a one or more consonants, first move those consonants to the end of the word and then add an `"ay"` sound to the end of the word.
+If a word begins with one or more consonants, first move those consonants to the end of the word and then add an `"ay"` sound to the end of the word.
 
 For example:
 
@@ -33,7 +33,7 @@ If a word starts with zero or more consonants followed by `"qu"`, first move tho
 
 For example:
 
-- `"quick"` -> `"ickqu"` -> `"ay"` (starts with `"qu"`, no preceding consonants)
+- `"quick"` -> `"ickqu"` -> `"ickquay"` (starts with `"qu"`, no preceding consonants)
 - `"square"` -> `"aresqu"` -> `"aresquay"` (starts with one consonant followed by `"qu`")
 
 ## Rule 4

exercises/practice/poker/.docs/instructions.md

@@ -2,6 +2,6 @@
 
 Pick the best hand(s) from a list of poker hands.
 
-See [wikipedia][poker-hands] for an overview of poker hands.
+See [Wikipedia][poker-hands] for an overview of poker hands.
 
 [poker-hands]: https://en.wikipedia.org/wiki/List_of_poker_hands

exercises/practice/protein-translation/.meta/tests.toml

@@ -87,11 +87,15 @@ description = "Translation stops if STOP codon in middle of three-codon sequence
 [2c2a2a60-401f-4a80-b977-e0715b23b93d]
 description = "Translation stops if STOP codon in middle of six-codon sequence"
 
+[f6f92714-769f-4187-9524-e353e8a41a80]
+description = "Sequence of two non-STOP codons does not translate to a STOP codon"
+
 [1e75ea2a-f907-4994-ae5c-118632a1cb0f]
 description = "Non-existing codon can't translate"
 
 [9eac93f3-627a-4c90-8653-6d0a0595bc6f]
 description = "Unknown amino acids, not part of a codon, can't translate"
+reimplements = "1e75ea2a-f907-4994-ae5c-118632a1cb0f"
 
 [9d73899f-e68e-4291-b1e2-7bf87c00f024]
 description = "Incomplete RNA sequence can't translate"

exercises/practice/protein-translation/src/test/java/ProteinTranslatorTest.java

@@ -171,6 +171,13 @@ public void testTranslationStopsIfStopCodonInMiddle2() {
                 .containsExactly("Tryptophan", "Cysteine", "Tyrosine");
     }
 
+    @Disabled("Remove to run test")
+    @Test
+    public void testSequenceOfTwoNonStopCodonsDoNotTranslateToAStopCodon() {
+        assertThat(proteinTranslator.translate("AUGAUG"))
+                .containsExactly("Methionine", "Methionine");
+    }
+
     @Disabled("Remove to run test")
     @Test
     public void testNonExistingCodonCantTranslate() {

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

@@ -1,39 +1,49 @@
-# This is an auto-generated file. Regular comments will be removed when this
-# file is regenerated. Regenerating will not touch any manually added keys,
-# so comments can be added in a "comment" key.
+# 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 = "queen with a valid position"
+description = "Test creation of Queens with valid and invalid positions -> queen with a valid position"
 
 [4e812d5d-b974-4e38-9a6b-8e0492bfa7be]
-description = "queen must have positive row"
+description = "Test creation of Queens with valid and invalid positions -> queen must have positive row"
 
 [f07b7536-b66b-4f08-beb9-4d70d891d5c8]
-description = "queen must have row on board"
+description = "Test creation of Queens with valid and invalid positions -> queen must have row on board"
 
 [15a10794-36d9-4907-ae6b-e5a0d4c54ebe]
-description = "queen must have positive column"
+description = "Test creation of Queens with valid and invalid positions -> queen must have positive column"
 
 [6907762d-0e8a-4c38-87fb-12f2f65f0ce4]
-description = "queen must have column on board"
+description = "Test creation of Queens with valid and invalid positions -> queen must have column on board"
 
 [33ae4113-d237-42ee-bac1-e1e699c0c007]
-description = "can not attack"
+description = "Test the ability of one queen to attack another -> cannot attack"
 
 [eaa65540-ea7c-4152-8c21-003c7a68c914]
-description = "can attack on same row"
+description = "Test the ability of one queen to attack another -> can attack on same row"
 
 [bae6f609-2c0e-4154-af71-af82b7c31cea]
-description = "can attack on same column"
+description = "Test the ability of one queen to attack another -> can attack on same column"
 
 [0e1b4139-b90d-4562-bd58-dfa04f1746c7]
-description = "can attack on first diagonal"
+description = "Test the ability of one queen to attack another -> can attack on first diagonal"
 
 [ff9b7ed4-e4b6-401b-8d16-bc894d6d3dcd]
-description = "can attack on second diagonal"
+description = "Test the ability of one queen to attack another -> can attack on second diagonal"
 
 [0a71e605-6e28-4cc2-aa47-d20a2e71037a]
-description = "can attack on third diagonal"
+description = "Test the ability of one queen to attack another -> can attack on third diagonal"
 
 [0790b588-ae73-4f1f-a968-dd0b34f45f86]
-description = "can attack on fourth diagonal"
+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"