Add exercise: killer-sudoku-helper (#2007)

Co-authored-by: Derk-Jan Karrenbeld <[email protected]>
Co-authored-by: Peter Tseng <[email protected]>

bin/format-array.rb

@@ -54,6 +54,9 @@
   'go-counting' => {
     'board' => :multi_line,
   },
+  'killer-sudoku-helper' => {
+    'expected' => :single_line,
+  },
   'minesweeper' => {
     'minefield' => :multi_line_unless_single,
     'expected' => :multi_line_unless_single,

exercises/killer-sudoku-helper/canonical-data.json

@@ -0,0 +1,179 @@
+{
+  "exercise": "killer-sudoku-helper",
+  "cases": [
+    {
+      "description": "Trivial 1-digit cages",
+      "cases": [
+        {
+          "uuid": "2aaa8f13-11b5-4054-b95c-a906e4d79fb6",
+          "description": "1",
+          "property": "combinations",
+          "input": {
+            "cage": {
+              "sum": 1,
+              "size": 1,
+              "exclude": []
+            }
+          },
+          "expected": [[1]]
+        },
+        {
+          "uuid": "4645da19-9fdd-4087-a910-a6ed66823563",
+          "description": "2",
+          "property": "combinations",
+          "input": {
+            "cage": {
+              "sum": 2,
+              "size": 1,
+              "exclude": []
+            }
+          },
+          "expected": [[2]]
+        },
+        {
+          "uuid": "07cfc704-f8aa-41b2-8f9a-cbefb674cb48",
+          "description": "3",
+          "property": "combinations",
+          "input": {
+            "cage": {
+              "sum": 3,
+              "size": 1,
+              "exclude": []
+            }
+          },
+          "expected": [[3]]
+        },
+        {
+          "uuid": "22b8b2ba-c4fd-40b3-b1bf-40aa5e7b5f24",
+          "description": "4",
+          "property": "combinations",
+          "input": {
+            "cage": {
+              "sum": 4,
+              "size": 1,
+              "exclude": []
+            }
+          },
+          "expected": [[4]]
+        },
+        {
+          "uuid": "b75d16e2-ff9b-464d-8578-71f73094cea7",
+          "description": "5",
+          "property": "combinations",
+          "input": {
+            "cage": {
+              "sum": 5,
+              "size": 1,
+              "exclude": []
+            }
+          },
+          "expected": [[5]]
+        },
+        {
+          "uuid": "bcbf5afc-4c89-4ff6-9357-07ab4d42788f",
+          "description": "6",
+          "property": "combinations",
+          "input": {
+            "cage": {
+              "sum": 6,
+              "size": 1,
+              "exclude": []
+            }
+          },
+          "expected": [[6]]
+        },
+        {
+          "uuid": "511b3bf8-186f-4e35-844f-c804d86f4a7a",
+          "description": "7",
+          "property": "combinations",
+          "input": {
+            "cage": {
+              "sum": 7,
+              "size": 1,
+              "exclude": []
+            }
+          },
+          "expected": [[7]]
+        },
+        {
+          "uuid": "bd09a60d-3aca-43bd-b6aa-6ccad01bedda",
+          "description": "8",
+          "property": "combinations",
+          "input": {
+            "cage": {
+              "sum": 8,
+              "size": 1,
+              "exclude": []
+            }
+          },
+          "expected": [[8]]
+        },
+        {
+          "uuid": "9b539f27-44ea-4ff8-bd3d-c7e136bee677",
+          "description": "9",
+          "property": "combinations",
+          "input": {
+            "cage": {
+              "sum": 9,
+              "size": 1,
+              "exclude": []
+            }
+          },
+          "expected": [[9]]
+        }
+      ]
+    },
+    {
+      "uuid": "0a8b2078-b3a4-4dbd-be0d-b180f503d5c3",
+      "description": "Cage with sum 45 contains all digits 1:9",
+      "property": "combinations",
+      "input": {
+        "cage": {
+          "sum": 45,
+          "size": 9,
+          "exclude": []
+        }
+      },
+      "expected": [[1, 2, 3, 4, 5, 6, 7, 8, 9]]
+    },
+    {
+      "uuid": "2635d7c9-c716-4da1-84f1-c96e03900142",
+      "description": "Cage with only 1 possible combination",
+      "property": "combinations",
+      "input": {
+        "cage": {
+          "sum": 7,
+          "size": 3,
+          "exclude": []
+        }
+      },
+      "expected": [[1, 2, 4]]
+    },
+    {
+      "uuid": "a5bde743-e3a2-4a0c-8aac-e64fceea4228",
+      "description": "Cage with several combinations",
+      "property": "combinations",
+      "input": {
+        "cage": {
+          "sum": 10,
+          "size": 2,
+          "exclude": []
+        }
+      },
+      "expected": [[1, 9], [2, 8], [3, 7], [4, 6]]
+    },
+    {
+      "uuid": "dfbf411c-737d-465a-a873-ca556360c274",
+      "description": "Cage with several combinations that is restricted",
+      "property": "combinations",
+      "input": {
+        "cage": {
+          "sum": 10,
+          "size": 2,
+          "exclude": [1, 4]
+        }
+      },
+      "expected": [[2, 8], [3, 7]]
+    }
+  ]
+}

exercises/killer-sudoku-helper/description.md

@@ -0,0 +1,55 @@
+# Description
+
+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](https://masteringsudoku.com/sudoku-rules-beginners/) 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](https://masteringsudoku.com/killer-sudoku/).
+
+## 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.](https://media.githubusercontent.com/media/exercism/v3-files/main/julia/killer-sudoku-helper/example1.png)
+
+## 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.](https://media.githubusercontent.com/media/exercism/v3-files/main/julia/killer-sudoku-helper/example2.png)
+
+## 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.](https://media.githubusercontent.com/media/exercism/v3-files/main/julia/killer-sudoku-helper/example3.png)
+
+## Trying it yourself
+
+If you want to give an approachable Killer Sudoku a go, you can try out [this puzzle](https://app.crackingthecryptic.com/sudoku/HqTBn3Pr6R) by Clover, featured by [Mark Goodliffe on Cracking The Cryptic on the 21st of June 2021](https://youtu.be/c_NjEbFEeW0?t=1180).
+
+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.

exercises/killer-sudoku-helper/metadata.toml

@@ -0,0 +1,3 @@
+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"