Add killer-sudoku-helper exercise

config.json

@@ -503,6 +503,14 @@
         "prerequisites": [],
         "difficulty": 5
       },
+      {
+        "slug": "killer-sudoku-helper",
+        "name": "Killer Sudoku Helper",
+        "uuid": "e12846f9-8905-406d-8b3d-b5e0fa4e3c0a",
+        "practices": [],
+        "prerequisites": [],
+        "difficulty": 5
+      },
       {
         "slug": "acronym",
         "name": "Acronym",

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

@@ -0,0 +1,85 @@
+# Instructions
+
+A friend of yours is learning how to solve Killer Sudokus (rules below) but struggling to figure out which digits can go in a cage.
+They ask you to help them out by writing a small program that lists all valid combinations for a given cage, and any constraints that affect the cage.
+
+To make the output of your program easy to read, the combinations it returns must be sorted.
+
+## Killer Sudoku Rules
+
+- [Standard Sudoku rules][sudoku-rules] apply.
+- The digits in a cage, usually marked by a dotted line, add up to the small number given in the corner of the cage.
+- A digit may only occur once in a cage.
+
+For a more detailed explanation, check out [this guide][killer-guide].
+
+## Example 1: Cage with only 1 possible combination
+
+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]
+
+## Example 2: Cage with several combinations
+
+In a 2-digit cage with a sum 10, there are 4 possible combinations:
+
+- 19
+- 28
+- 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]
+
+## Example 3: Cage with several combinations that is restricted
+
+In a 2-digit cage with a sum 10, where the column already contains a 1 and a 4, there are 2 possible combinations:
+
+- 28
+- 37
+
+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]
+
+## Trying it yourself
+
+If you want to give an approachable Killer Sudoku a go, you can try out [this puzzle][clover-puzzle] by Clover, featured by [Mark Goodliffe on Cracking The Cryptic on the 21st of June 2021][goodliffe-video].
+
+You can also find Killer Sudokus in varying difficulty in numerous newspapers, as well as Sudoku apps, books and websites.
+
+## Credit
+
+The screenshots above have been generated using [F-Puzzles.com](https://www.f-puzzles.com/), a Puzzle Setting Tool by Eric Fox.
+
+[sudoku-rules]: https://masteringsudoku.com/sudoku-rules-beginners/
+[killer-guide]: https://masteringsudoku.com/killer-sudoku/
+[one-solution-img]: https://assets.exercism.org/images/exercises/killer-sudoku-helper/example1.png
+[four-solutions-img]: https://assets.exercism.org/images/exercises/killer-sudoku-helper/example2.png
+[not-possible-img]: https://assets.exercism.org/images/exercises/killer-sudoku-helper/example3.png
+[clover-puzzle]: https://app.crackingthecryptic.com/sudoku/HqTBn3Pr6R
+[goodliffe-video]: https://youtu.be/c_NjEbFEeW0?t=1180

exercises/practice/killer-sudoku-helper/.meta/Example.roc

@@ -0,0 +1,27 @@
+module [combinations]
+
+Combination : List U8
+
+combinations : { sum : U8, size : U8, exclude ? List U8 } -> List Combination
+combinations = \{ sum, size, exclude ? [] } ->
+    help = \target, digits ->
+        if target == 0 then
+            [[]]
+            else
+
+        when digits is
+            [] -> [[]]
+            [single] -> if single == target then [[single]] else []
+            [first, .. as rest] ->
+                if first > target then
+                    []
+                    else
+
+                help (target - first) rest
+                |> List.map \combi -> combi |> List.prepend first
+                |> List.concat (help target rest)
+    availableDigits =
+        [1, 2, 3, 4, 5, 6, 7, 8, 9]
+        |> List.dropIf \digit -> exclude |> List.contains digit
+    help sum availableDigits
+    |> List.keepIf \combi -> List.len combi == size |> Num.toU64

exercises/practice/killer-sudoku-helper/.meta/config.json

@@ -0,0 +1,19 @@
+{
+  "authors": [
+    "ageron"
+  ],
+  "files": {
+    "solution": [
+      "KillerSudokuHelper.roc"
+    ],
+    "test": [
+      "killer-sudoku-helper-test.roc"
+    ],
+    "example": [
+      ".meta/Example.roc"
+    ]
+  },
+  "blurb": "Write a tool that makes it easier to solve Killer Sudokus",
+  "source": "Created by Sascha Mann, Jeremy Walker, and BethanyG for the Julia track on Exercism.",
+  "source_url": "https://github.com/exercism/julia/pull/413"
+}

exercises/practice/killer-sudoku-helper/.meta/template.j2

@@ -0,0 +1,31 @@
+{%- import "generator_macros.j2" as macros with context -%}
+{{ macros.canonical_ref() }}
+{{ macros.header() }}
+
+import {{ exercise | to_pascal }} exposing [combinations]
+
+{% macro to_cage(cage) -%}
+{ sum: {{ cage["sum"] }}, size: {{ cage["size"] }}
+{%- if cage["exclude"] != [] -%}
+, exclude: {{ cage["exclude"] | to_roc }}
+{%- endif %} }
+{%- endmacro %}
+
+{% for supercase in cases %}
+## {{ supercase["description"] }}
+{%- if supercase["cases"] -%}
+{%- set cases = supercase["cases"] -%}
+{%- else -%}
+{%- set cases = [supercase] -%}
+{%- endif -%}
+{%- for case in cases %}
+{%- if case["description"] != supercase["description"] %}
+# {{ case["description"] }}
+{%- endif %}
+expect
+    result = {{ case["property"] }} {{ to_cage(case["input"]["cage"]) }}
+    result == {{ case["expected"] | to_roc }}
+
+{% endfor -%}
+{%- endfor %}
+

exercises/practice/killer-sudoku-helper/.meta/tests.toml

@@ -0,0 +1,49 @@
+# 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.
+
+[2aaa8f13-11b5-4054-b95c-a906e4d79fb6]
+description = "Trivial 1-digit cages -> 1"
+
+[4645da19-9fdd-4087-a910-a6ed66823563]
+description = "Trivial 1-digit cages -> 2"
+
+[07cfc704-f8aa-41b2-8f9a-cbefb674cb48]
+description = "Trivial 1-digit cages -> 3"
+
+[22b8b2ba-c4fd-40b3-b1bf-40aa5e7b5f24]
+description = "Trivial 1-digit cages -> 4"
+
+[b75d16e2-ff9b-464d-8578-71f73094cea7]
+description = "Trivial 1-digit cages -> 5"
+
+[bcbf5afc-4c89-4ff6-9357-07ab4d42788f]
+description = "Trivial 1-digit cages -> 6"
+
+[511b3bf8-186f-4e35-844f-c804d86f4a7a]
+description = "Trivial 1-digit cages -> 7"
+
+[bd09a60d-3aca-43bd-b6aa-6ccad01bedda]
+description = "Trivial 1-digit cages -> 8"
+
+[9b539f27-44ea-4ff8-bd3d-c7e136bee677]
+description = "Trivial 1-digit cages -> 9"
+
+[0a8b2078-b3a4-4dbd-be0d-b180f503d5c3]
+description = "Cage with sum 45 contains all digits 1:9"
+
+[2635d7c9-c716-4da1-84f1-c96e03900142]
+description = "Cage with only 1 possible combination"
+
+[a5bde743-e3a2-4a0c-8aac-e64fceea4228]
+description = "Cage with several combinations"
+
+[dfbf411c-737d-465a-a873-ca556360c274]
+description = "Cage with several combinations that is restricted"

exercises/practice/killer-sudoku-helper/KillerSudokuHelper.roc

@@ -0,0 +1,7 @@
+module [combinations]
+
+Combination : List U8
+
+combinations : { sum : U8, size : U8, exclude ? List U8 } -> List Combination
+combinations = \{ sum, size, exclude ? [] } ->
+    crash "Please implement the 'combinations' function"

exercises/practice/killer-sudoku-helper/killer-sudoku-helper-test.roc

@@ -0,0 +1,78 @@
+# These tests are auto-generated with test data from:
+# https://github.com/exercism/problem-specifications/tree/main/exercises/killer-sudoku-helper/canonical-data.json
+# File last updated on 2024-09-28
+app [main] {
+    pf: platform "https://github.com/roc-lang/basic-cli/releases/download/0.15.0/SlwdbJ-3GR7uBWQo6zlmYWNYOxnvo8r6YABXD-45UOw.tar.br",
+}
+
+main =
+    Task.ok {}
+
+import KillerSudokuHelper exposing [combinations]
+
+## Trivial 1-digit cages
+# 1
+expect
+    result = combinations { sum: 1, size: 1 }
+    result == [[1]]
+
+# 2
+expect
+    result = combinations { sum: 2, size: 1 }
+    result == [[2]]
+
+# 3
+expect
+    result = combinations { sum: 3, size: 1 }
+    result == [[3]]
+
+# 4
+expect
+    result = combinations { sum: 4, size: 1 }
+    result == [[4]]
+
+# 5
+expect
+    result = combinations { sum: 5, size: 1 }
+    result == [[5]]
+
+# 6
+expect
+    result = combinations { sum: 6, size: 1 }
+    result == [[6]]
+
+# 7
+expect
+    result = combinations { sum: 7, size: 1 }
+    result == [[7]]
+
+# 8
+expect
+    result = combinations { sum: 8, size: 1 }
+    result == [[8]]
+
+# 9
+expect
+    result = combinations { sum: 9, size: 1 }
+    result == [[9]]
+
+## Cage with sum 45 contains all digits 1:9
+expect
+    result = combinations { sum: 45, size: 9 }
+    result == [[1, 2, 3, 4, 5, 6, 7, 8, 9]]
+
+## Cage with only 1 possible combination
+expect
+    result = combinations { sum: 7, size: 3 }
+    result == [[1, 2, 4]]
+
+## Cage with several combinations
+expect
+    result = combinations { sum: 10, size: 2 }
+    result == [[1, 9], [2, 8], [3, 7], [4, 6]]
+
+## Cage with several combinations that is restricted
+expect
+    result = combinations { sum: 10, size: 2, exclude: [1, 4] }
+    result == [[2, 8], [3, 7]]
+