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rabestroJegors Cemisovs
rabestro
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Jegors Cemisovs
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Killer sudoku helper (#862)
* Add detailed instructions and examples for the Killer Sudoku Helper exercise * Add example implementation for Killer Sudoku Helper exercise * Add configuration and tests for Killer Sudoku Helper exercise --------- Co-authored-by: Jegors Cemisovs <[email protected]>
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‎config.json

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"practices": [],
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"prerequisites": [],
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"difficulty": 3
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},
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{
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"slug": "killer-sudoku-helper",
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"name": "Killer Sudoku Helper",
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"uuid": "6c0c1b40-cca6-414b-a3f9-3f0c0ddb2d6d",
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"practices": [],
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"prerequisites": [],
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"difficulty": 4
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}
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]
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},

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

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# Instructions
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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.
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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.
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To make the output of your program easy to read, the combinations it returns must be sorted.
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## Killer Sudoku Rules
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- [Standard Sudoku rules][sudoku-rules] apply.
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- The digits in a cage, usually marked by a dotted line, add up to the small number given in the corner of the cage.
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- A digit may only occur once in a cage.
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For a more detailed explanation, check out [this guide][killer-guide].
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## Example 1: Cage with only 1 possible combination
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In a 3-digit cage with a sum of 7, there is only one valid combination: 124.
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- 1 + 2 + 4 = 7
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- Any other combination that adds up to 7, e.g. 232, would violate the rule of not repeating digits within a cage.
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![Sudoku grid, with three killer cages that are marked as grouped together.
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The first killer cage is in the 3×3 box in the top left corner of the grid.
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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.
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The numbers are highlighted in red to indicate a mistake.
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The second killer cage is in the central 3×3 box of the grid.
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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.
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None of the numbers in this cage are highlighted and therefore don't contain any mistakes.
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The third killer cage follows the outside corner of the central 3×3 box of the grid.
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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.
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The top right cell of the cage contains a 3.
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The bottom right cell of the cage contains a 2, highlighted in red. All other cells are empty.][one-solution-img]
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## Example 2: Cage with several combinations
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In a 2-digit cage with a sum 10, there are 4 possible combinations:
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- 19
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- 28
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- 37
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- 46
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![Sudoku grid, all squares empty except for the middle column, column 5, which has 8 rows filled.
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Each continguous two rows form a killer cage and are marked as grouped together.
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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.
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Second group is a cell with value 2 and a pencil mark of 10, cell with value 8.
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Third group is a cell with value 3 and a pencil mark of 10, cell with value 7.
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Fourth group is a cell with value 4 and a pencil mark of 10, cell with value 6.
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The last cell in the column is empty.][four-solutions-img]
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## Example 3: Cage with several combinations that is restricted
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In a 2-digit cage with a sum 10, where the column already contains a 1 and a 4, there are 2 possible combinations:
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- 28
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- 37
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19 and 46 are not possible due to the 1 and 4 in the column according to standard Sudoku rules.
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![Sudoku grid, all squares empty except for the middle column, column 5, which has 8 rows filled.
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The first row contains a 4, the second is empty, and the third contains a 1.
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The 1 is highlighted in red to indicate a mistake.
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The last 6 rows in the column form killer cages of two cells each.
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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.
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Second group is a cell with value 3 and a pencil mark of 10, cell with value 7.
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Third group is a cell with value 1, highlighted in red, and a pencil mark of 10, cell with value 9.][not-possible-img]
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## Trying it yourself
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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].
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You can also find Killer Sudokus in varying difficulty in numerous newspapers, as well as Sudoku apps, books and websites.
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## Credit
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The screenshots above have been generated using [F-Puzzles.com](https://www.f-puzzles.com/), a Puzzle Setting Tool by Eric Fox.
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[sudoku-rules]: https://masteringsudoku.com/sudoku-rules-beginners/
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[killer-guide]: https://masteringsudoku.com/killer-sudoku/
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[one-solution-img]: https://assets.exercism.org/images/exercises/killer-sudoku-helper/example1.png
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[four-solutions-img]: https://assets.exercism.org/images/exercises/killer-sudoku-helper/example2.png
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[not-possible-img]: https://assets.exercism.org/images/exercises/killer-sudoku-helper/example3.png
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[clover-puzzle]: https://app.crackingthecryptic.com/sudoku/HqTBn3Pr6R
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[goodliffe-video]: https://youtu.be/c_NjEbFEeW0?t=1180

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

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import KillerSudokuHelper.MaxDigit
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case class KillerSudokuHelper(exclude: Set[Int]):
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private def generateRecursive(currentStartDigit: Int, remainingSum: Int, remainingSize: Int): List[List[Int]] =
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if remainingSize == 1 then
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if currentStartDigit <= remainingSum && remainingSum <= MaxDigit && !exclude.contains(remainingSum) then
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List(List(remainingSum))
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else List()
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else
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val maxPossibleFirstDigit = MaxDigit - remainingSize + 1
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(currentStartDigit to maxPossibleFirstDigit).toList
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.filterNot(digit => exclude.contains(digit))
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.flatMap(digit => generateRecursive(digit + 1, remainingSum - digit, remainingSize - 1).map(s => digit :: s))
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object KillerSudokuHelper:
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val MaxDigit = 9
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def combinations(sum: Int, size: Int, exclude: List[Int] = Nil): List[List[Int]] =
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KillerSudokuHelper(exclude.toSet).generateRecursive(1, sum, size)

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

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{
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"authors": [
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"rabestro"
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],
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"files": {
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"solution": [
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"src/main/scala/KillerSudokuHelper.scala"
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],
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"test": [
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"src/test/scala/KillerSudokuHelperTest.scala"
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],
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"example": [
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".meta/Example.scala"
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],
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"invalidator": [
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"build.sbt"
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]
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},
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"blurb": "Write a tool that makes it easier to solve Killer Sudokus",
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"source": "Created by Sascha Mann, Jeremy Walker, and BethanyG for the Julia track on Exercism.",
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"source_url": "https://github.com/exercism/julia/pull/413"
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}

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

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# This is an auto-generated file.
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#
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# Regenerating this file via `configlet sync` will:
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# - Recreate every `description` key/value pair
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# - Recreate every `reimplements` key/value pair, where they exist in problem-specifications
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# - Remove any `include = true` key/value pair (an omitted `include` key implies inclusion)
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# - Preserve any other key/value pair
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#
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# As user-added comments (using the # character) will be removed when this file
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# is regenerated, comments can be added via a `comment` key.
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[2aaa8f13-11b5-4054-b95c-a906e4d79fb6]
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description = "Trivial 1-digit cages -> 1"
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[4645da19-9fdd-4087-a910-a6ed66823563]
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description = "Trivial 1-digit cages -> 2"
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[07cfc704-f8aa-41b2-8f9a-cbefb674cb48]
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description = "Trivial 1-digit cages -> 3"
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[22b8b2ba-c4fd-40b3-b1bf-40aa5e7b5f24]
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description = "Trivial 1-digit cages -> 4"
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[b75d16e2-ff9b-464d-8578-71f73094cea7]
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description = "Trivial 1-digit cages -> 5"
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[bcbf5afc-4c89-4ff6-9357-07ab4d42788f]
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description = "Trivial 1-digit cages -> 6"
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[511b3bf8-186f-4e35-844f-c804d86f4a7a]
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description = "Trivial 1-digit cages -> 7"
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[bd09a60d-3aca-43bd-b6aa-6ccad01bedda]
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description = "Trivial 1-digit cages -> 8"
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[9b539f27-44ea-4ff8-bd3d-c7e136bee677]
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description = "Trivial 1-digit cages -> 9"
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[0a8b2078-b3a4-4dbd-be0d-b180f503d5c3]
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description = "Cage with sum 45 contains all digits 1:9"
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[2635d7c9-c716-4da1-84f1-c96e03900142]
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description = "Cage with only 1 possible combination"
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[a5bde743-e3a2-4a0c-8aac-e64fceea4228]
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description = "Cage with several combinations"
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[dfbf411c-737d-465a-a873-ca556360c274]
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description = "Cage with several combinations that is restricted"

‎exercises/practice/killer-sudoku-helper/build.sbt

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scalaVersion := "3.4.2"
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libraryDependencies += "org.scalatest" %% "scalatest" % "3.2.19" % Test

‎exercises/practice/killer-sudoku-helper/src/main/scala/KillerSudokuHelper.scala

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‎exercises/practice/killer-sudoku-helper/src/test/scala/KillerSudokuHelperTest.scala

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// Generated by AI (Gemini)
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import org.scalatest.flatspec.AnyFlatSpec
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import org.scalatest.matchers.should.Matchers
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class KillerSudokuHelperTest extends AnyFlatSpec with Matchers {
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behavior of "KillerSudokuHelper.combinations"
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it should "handle trivial 1-digit cage: sum 1, size 1, no exclusions" in {
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val sum = 1
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val size = 1
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val exclude = List()
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KillerSudokuHelper.combinations(sum, size, exclude) should be(List(List(1)))
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}
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it should "handle trivial 1-digit cage: sum 2, size 1, no exclusions" in {
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pending
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val sum = 2
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val size = 1
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val exclude = List()
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KillerSudokuHelper.combinations(sum, size, exclude) should be(List(List(2)))
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}
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it should "handle trivial 1-digit cage: sum 3, size 1, no exclusions" in {
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pending
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val sum = 3
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val size = 1
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val exclude = List()
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KillerSudokuHelper.combinations(sum, size, exclude) should be(List(List(3)))
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}
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it should "handle trivial 1-digit cage: sum 4, size 1, no exclusions" in {
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pending
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val sum = 4
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val size = 1
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val exclude = List()
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KillerSudokuHelper.combinations(sum, size, exclude) should be(List(List(4)))
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}
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it should "handle trivial 1-digit cage: sum 5, size 1, no exclusions" in {
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pending
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val sum = 5
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val size = 1
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val exclude = List()
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KillerSudokuHelper.combinations(sum, size, exclude) should be(List(List(5)))
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}
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it should "handle trivial 1-digit cage: sum 6, size 1, no exclusions" in {
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pending
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val sum = 6
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val size = 1
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val exclude = List()
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KillerSudokuHelper.combinations(sum, size, exclude) should be(List(List(6)))
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}
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it should "handle trivial 1-digit cage: sum 7, size 1, no exclusions" in {
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pending
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val sum = 7
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val size = 1
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val exclude = List()
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KillerSudokuHelper.combinations(sum, size, exclude) should be(List(List(7)))
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}
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it should "handle trivial 1-digit cage: sum 8, size 1, no exclusions" in {
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pending
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val sum = 8
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val size = 1
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val exclude = List()
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KillerSudokuHelper.combinations(sum, size, exclude) should be(List(List(8)))
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}
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it should "handle trivial 1-digit cage: sum 9, size 1, no exclusions" in {
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pending
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val sum = 9
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val size = 1
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val exclude = List()
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KillerSudokuHelper.combinations(sum, size, exclude) should be(List(List(9)))
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}
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it should "Cage with sum 45 contains all digits 1:9" in {
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pending
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val sum = 45
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val size = 9
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val exclude = List()
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KillerSudokuHelper.combinations(sum, size, exclude) should be(List(List(1, 2, 3, 4, 5, 6, 7, 8, 9)))
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}
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it should "Cage with only 1 possible combination" in {
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pending
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val sum = 7
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val size = 3
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val exclude = List()
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KillerSudokuHelper.combinations(sum, size, exclude) should be(List(List(1, 2, 4)))
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}
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it should "Cage with several combinations" in {
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pending
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val sum = 10
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val size = 2
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val exclude = List()
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KillerSudokuHelper.combinations(sum, size, exclude) should be(List(List(1, 9), List(2, 8), List(3, 7), List(4, 6)))
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}
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it should "Cage with several combinations that is restricted" in {
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pending
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val sum = 10
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val size = 2
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val exclude = List(1, 4)
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KillerSudokuHelper.combinations(sum, size, exclude) should be(List(List(2, 8), List(3, 7)))
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}
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}

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