[New exercise] Killer sudoku helper (#2549)

* Adding autogenerated-files

* Add scaffolding

* Add tests

* Add proof solution

* Update config.json

* I knew i was forgetting something...

config.json

@@ -2642,6 +2642,20 @@
           "classes",
           "callbacks"
         ]
+      },
+      {
+        "slug": "killer-sudoku-helper",
+        "name": "Killer Sudoku Helper",
+        "uuid": "4b6b00cd-62f8-4e9e-b59d-79f153f8efb5",
+        "practices": [],
+        "prerequisites": [
+          "conditionals",
+          "recursion",
+          "loops",
+          "numbers",
+          "lists"
+        ],
+        "difficulty": 5
       }
     ]
   },

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/.eslintrc

@@ -0,0 +1,14 @@
+{
+  "root": true,
+  "extends": "@exercism/eslint-config-javascript",
+  "env": {
+    "jest": true
+  },
+  "overrides": [
+    {
+      "files": [".meta/proof.ci.js", ".meta/exemplar.js", "*.spec.js"],
+      "excludedFiles": ["custom.spec.js"],
+      "extends": "@exercism/eslint-config-javascript/maintainers"
+    }
+  ]
+}

exercises/practice/killer-sudoku-helper/.gitignore

@@ -0,0 +1,5 @@
+/node_modules
+/bin/configlet
+/bin/configlet.exe
+/pnpm-lock.yaml
+/yarn.lock

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

@@ -0,0 +1,19 @@
+{
+  "authors": [
+    "Cool-Katt"
+  ],
+  "files": {
+    "solution": [
+      "killer-sudoku-helper.js"
+    ],
+    "test": [
+      "killer-sudoku-helper.spec.js"
+    ],
+    "example": [
+      ".meta/proof.ci.js"
+    ]
+  },
+  "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/proof.ci.js

@@ -0,0 +1,28 @@
+export const combinations = (cage) => {
+  const { sum, size, exclude } = cage;
+  const result = [];
+  const digits = [...Array(10).keys()]
+    .slice(1)
+    .filter((d) => !exclude.includes(d));
+
+  function findCombinations(remainingSum, index, combination) {
+    if (remainingSum === 0 && combination.length === size) {
+      result.push(combination);
+      return;
+    }
+
+    for (let i = index; i < digits.length; i++) {
+      const digit = digits[i];
+      if (digit > remainingSum) {
+        break;
+      }
+      if (combination.includes(digit)) {
+        continue;
+      }
+      findCombinations(remainingSum - digit, i + 1, [...combination, digit]);
+    }
+  }
+
+  findCombinations(sum, 0, []);
+  return result;
+};

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/.npmrc

@@ -0,0 +1 @@
+audit=false

exercises/practice/killer-sudoku-helper/LICENSE

@@ -0,0 +1,21 @@
+MIT License
+
+Copyright (c) 2021 Exercism
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

exercises/practice/killer-sudoku-helper/babel.config.js

@@ -0,0 +1,4 @@
+module.exports = {
+  presets: ['@exercism/babel-preset-javascript'],
+  plugins: [],
+};

exercises/practice/killer-sudoku-helper/killer-sudoku-helper.js

@@ -0,0 +1,8 @@
+//
+// This is only a SKELETON file for the 'Killer Sudoku Helper' exercise. It's been provided as a
+// convenience to get you started writing code faster.
+//
+
+export const combinations = (cage) => {
+  throw new Error('Remove this statement and implement this function');
+};