[New Exercise]: Killer Sudoku Helper (#284)

* [New Exercise]: Killer Sudoku Helper

* Update test file

-Fix some blank lines and update test file

config.json

@@ -784,6 +784,14 @@
         "prerequisites": [],
         "difficulty": 4
       },
+      {
+        "slug": "killer-sudoku-helper",
+        "name": "Killer Sudoku Helper",
+        "uuid": "cdfc017a-30aa-4dcd-aa79-8a7dfcd7bca1",
+        "practices": [],
+        "prerequisites": [],
+        "difficulty": 4
+      },
       {
         "slug": "change",
         "name": "Change",

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

@@ -0,0 +1,63 @@
+# 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/KillerSudokuHelper.example.ps1

@@ -0,0 +1,64 @@
+Function Invoke-KillerSudokuHelper() {
+    <#
+    .SYNOPSIS
+    Implement a function to help solve killer sudoku.
+
+    .DESCRIPTION
+    Given a cage of certain size, a sum and an array of excluded number, follow the rules and find all possible combinations to fill the cage.
+    To make the output of your program easy to read, the combinations it returns must be sorted.
+
+    For example:
+    7, [][][], No exclusion => Only possible solution is [1][2][4]
+    [1][1][5], [1][3][3], [2][2][3] are all in violation of the "A digit may only occur once in a cage" rule.
+
+    .PARAMETER Sum
+    The target sum: total of all number in a cage.
+
+    .PARAMETER Size
+    The size of the cage: total cells available for the sum.
+
+    .PARAMETER Exlude
+    An array of number that should be excluded from consideration for the sum.
+
+    .EXAMPLE
+    Invoke-KillerSudokuHelper -Sum 5 -Size 2 -Exclude @(1)
+    Return: @( ,@(2, 3))
+    #>
+    [CmdletBinding()]
+    Param(
+        [int]$Sum,
+        [int]$Size,
+        [int[]]$Exclude
+    )
+    $potential = 1..9 | Where-Object {$_ -le $sum -and $Exclude -notcontains $_}
+
+    $combinations = Get-Combination -Target $Sum -Size $Size -Range $potential -Result @()
+    $combinations
+}
+
+function Get-Combination {
+    <#
+    .DESCRIPTION
+    Recursive function to help fincing all posible solutions.
+    #>
+    param (
+        [int]$Target,
+        [int]$Size,
+        [int[]]$Range,
+        [int[]]$Result
+    )
+    if ($Result.Count -eq $Size -and $Target -eq 0) {
+        return (,$Result)
+    }
+
+    for ($i = 0; $i -lt $Range.Count; $i++) {
+        $num = $Range[$i]
+        if ($num -le $Target) {
+            $newTarget = $Target - $num
+            $newResult = $Result + $num
+
+            $newRange = $Range[($i + 1)..($Range.Count - 1)]
+            Get-Combination $newTarget $Size $newRange $newResult
+        }
+    }
+}

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

@@ -0,0 +1,19 @@
+{
+  "authors": [
+    "glaxxie"
+  ],
+  "files": {
+    "solution": [
+      "KillerSudokuHelper.ps1"
+    ],
+    "test": [
+      "KillerSudokuHelper.tests.ps1"
+    ],
+    "example": [
+      ".meta/KillerSudokuHelper.example.ps1"
+    ]
+  },
+  "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/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.ps1

@@ -0,0 +1,35 @@
+Function Invoke-KillerSudokuHelper() {
+    <#
+    .SYNOPSIS
+    Implement a function to help solve killer sudoku.
+
+    .DESCRIPTION
+    Given a cage of certain size, a sum and an array of excluded number, follow the rules and find all possible combinations to fill the cage.
+    To make the output of your program easy to read, the combinations it returns must be sorted.
+
+    For example:
+    7, [][][], No exclusion => Only possible solution is [1][2][4]
+    [1][1][5], [1][3][3], [2][2][3] are all in violation of the "A digit may only occur once in a cage" rule.
+
+    .PARAMETER Sum
+    The target sum: total of all number in a cage.
+
+    .PARAMETER Size
+    The size of the cage: total cells available for the sum.
+
+    .PARAMETER Exlude
+    An array of number that should be excluded from consideration for the sum.
+
+    .EXAMPLE
+    Invoke-KillerSudokuHelper -Sum 5 -Size 2 -Exclude @(1)
+    Return: @( ,@(2, 3))
+    #>
+    [CmdletBinding()]
+    Param(
+        [int]$Sum,
+        [int]$Size,
+        [int[]]$Exclude
+    )
+
+    Throw "Please implement this function"
+}

exercises/practice/killer-sudoku-helper/KillerSudokuHelper.tests.ps1

@@ -0,0 +1,98 @@
+BeforeAll {
+    . "./KillerSudokuHelper.ps1"
+}
+
+Describe "KillerSudokuHelper test cases" {
+    Context "Trivial 1-digit cages" {
+        It "Trivial 1-digit cages -> 1" {
+            $got  = Invoke-KillerSudokuHelper -Sum 1 -Size 1 -Exclude @()
+            $want = @( @(1))
+
+            $got | Should -BeExactly $want
+        }
+
+        It "Trivial 1-digit cages -> 2" {
+            $got  = Invoke-KillerSudokuHelper -Sum 2 -Size 1 -Exclude @()
+            $want = @( @(2))
+
+            $got | Should -BeExactly $want
+        }
+
+        It "Trivial 1-digit cages -> 3" {
+            $got  = Invoke-KillerSudokuHelper -Sum 3 -Size 1 -Exclude @()
+            $want = @( @(3))
+
+            $got | Should -BeExactly $want
+        }
+
+        It "Trivial 1-digit cages -> 4" {
+            $got  = Invoke-KillerSudokuHelper -Sum 4 -Size 1 -Exclude @()
+            $want = @( @(4))
+
+            $got | Should -BeExactly $want
+        }
+
+        It "Trivial 1-digit cages -> 5" {
+            $got  = Invoke-KillerSudokuHelper -Sum 5 -Size 1 -Exclude @()
+            $want = @( @(5))
+
+            $got | Should -BeExactly $want
+        }
+
+        It "Trivial 1-digit cages -> 6" {
+            $got  = Invoke-KillerSudokuHelper -Sum 6 -Size 1 -Exclude @()
+            $want = @( @(6))
+
+            $got | Should -BeExactly $want
+        }
+
+        It "Trivial 1-digit cages -> 7" {
+            $got  = Invoke-KillerSudokuHelper -Sum 7 -Size 1 -Exclude @()
+            $want = @( @(7))
+
+            $got | Should -BeExactly $want
+        }
+
+        It "Trivial 1-digit cages -> 8" {
+            $got  = Invoke-KillerSudokuHelper -Sum 8 -Size 1 -Exclude @()
+            $want = @( @(8))
+
+            $got | Should -BeExactly $want
+        }
+
+        It "Trivial 1-digit cages -> 9" {
+            $got  = Invoke-KillerSudokuHelper -Sum 9 -Size 1 -Exclude @()
+            $want = @( @(9))
+
+            $got | Should -BeExactly $want
+        }
+    }
+
+    It "Cage with sum 45 contains all digits 1:9" {
+        $got  = Invoke-KillerSudokuHelper -Sum 45 -Size 9 -Exclude @()
+        $want = @( @(1, 2, 3, 4, 5, 6, 7, 8, 9))
+
+        $got | Should -BeExactly $want
+    }
+
+    It "Cage with only 1 possible combination" {
+        $got  = Invoke-KillerSudokuHelper -Sum 7 -Size 3 -Exclude @()
+        $want = @( @(1, 2, 4))
+
+        $got | Should -BeExactly $want
+    }
+
+    It "Cage with several combinations" {
+        $got  = Invoke-KillerSudokuHelper -Sum 10 -Size 2 -Exclude @()
+        $want = @( @(1, 9), @(2, 8), @(3, 7), @(4, 6))
+
+        $got | Should -BeExactly $want
+    }
+
+    It "Cage with several combinations that is restricted" {
+        $got  = Invoke-KillerSudokuHelper -Sum 10 -Size 2 -Exclude @(1, 4)
+        $want = @( @(2, 8), @(3, 7))
+
+        $got | Should -BeExactly $want
+    }
+}