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ErikSchierboomErikSchierboom
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Add killer-sudoku-helper exercise (#787)
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‎config.json‎

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],
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"difficulty": 6
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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": "c8b4c5e9-6567-48fe-b01a-462cbbf84805",
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"practices": [],
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"prerequisites": [
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"numbers",
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"conditionals",
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"vectors"
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],
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"difficulty": 6
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},
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{
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"slug": "robot-simulator",
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"name": "Robot Simulator",

‎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/config.json‎

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{
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"authors": [
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"erikschierboom"
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],
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"files": {
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"solution": [
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"src/killer_sudoku_helper.clj"
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],
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"test": [
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"test/killer_sudoku_helper_test.clj"
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],
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"example": [
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".meta/example.clj"
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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/example.clj‎

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(ns killer-sudoku-helper)
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(def digits (set (range 1 10)))
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(defn combinations-of-size [coll size]
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(cond
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(zero? size) '(())
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(empty? coll) '()
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:else (concat (map (fn [x] (cons (first coll) x))
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(combinations-of-size (rest coll) (dec size)))
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(combinations-of-size (rest coll) size))))
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(defn combinations [{:keys [sum size exclude]}]
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(let [valid-digits (apply disj digits exclude)]
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(sort
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(for [combination (combinations-of-size valid-digits size)
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:when (= sum (apply + combination))]
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(into [] (sort combination))))))

‎exercises/practice/killer-sudoku-helper/.meta/generator.tpl‎

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(ns killer-sudoku-helper-test
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(:require [clojure.test :refer [deftest testing is]]
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killer-sudoku-helper))
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{{#test_cases.combinations}}
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(deftest combinations_test_{{idx}}
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(testing {{description}}
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(is (= {{expected}} (killer-sudoku-helper/combinations {:sum {{input.cage.sum}} :size {{input.cage.size}} :exclude {{input.cage.exclude~}} })))))
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{{/test_cases.combinations}}

‎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/deps.edn‎

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{:aliases {:test {:extra-paths ["test"]
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:extra-deps {io.github.cognitect-labs/test-runner
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{:git/url "https://github.com/cognitect-labs/test-runner.git"
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:sha "705ad25bbf0228b1c38d0244a36001c2987d7337"}}
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:main-opts ["-m" "cognitect.test-runner"]
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:exec-fn cognitect.test-runner.api/test}}}

‎exercises/practice/killer-sudoku-helper/project.clj‎

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(defproject killer-sudoku-helper "0.1.0-SNAPSHOT"
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:description "killer-sudoku-helper exercise."
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:url "https://github.com/exercism/clojure/tree/main/exercises/practice/killer-sudoku-helper"
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:dependencies [[org.clojure/clojure "1.11.1"]])

‎exercises/practice/killer-sudoku-helper/src/killer_sudoku_helper.clj‎

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(ns killer-sudoku-helper)
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(defn combinations
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"Returns the valid combinations for a given cage."
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[cage]
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;; function body
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)

‎exercises/practice/killer-sudoku-helper/test/killer_sudoku_helper_test.clj‎

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(ns killer-sudoku-helper-test
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(:require [clojure.test :refer [deftest testing is]]
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killer-sudoku-helper))
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(deftest combinations_test_1
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(testing "Trivial 1-digit cages ▶ 1"
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(is (= [[1]] (killer-sudoku-helper/combinations {:sum 1 :size 1 :exclude []})))))
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(deftest combinations_test_2
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(testing "Trivial 1-digit cages ▶ 2"
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(is (= [[2]] (killer-sudoku-helper/combinations {:sum 2 :size 1 :exclude []})))))
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(deftest combinations_test_3
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(testing "Trivial 1-digit cages ▶ 3"
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(is (= [[3]] (killer-sudoku-helper/combinations {:sum 3 :size 1 :exclude []})))))
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(deftest combinations_test_4
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(testing "Trivial 1-digit cages ▶ 4"
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(is (= [[4]] (killer-sudoku-helper/combinations {:sum 4 :size 1 :exclude []})))))
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(deftest combinations_test_5
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(testing "Trivial 1-digit cages ▶ 5"
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(is (= [[5]] (killer-sudoku-helper/combinations {:sum 5 :size 1 :exclude []})))))
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(deftest combinations_test_6
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(testing "Trivial 1-digit cages ▶ 6"
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(is (= [[6]] (killer-sudoku-helper/combinations {:sum 6 :size 1 :exclude []})))))
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(deftest combinations_test_7
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(testing "Trivial 1-digit cages ▶ 7"
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(is (= [[7]] (killer-sudoku-helper/combinations {:sum 7 :size 1 :exclude []})))))
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(deftest combinations_test_8
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(testing "Trivial 1-digit cages ▶ 8"
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(is (= [[8]] (killer-sudoku-helper/combinations {:sum 8 :size 1 :exclude []})))))
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(deftest combinations_test_9
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(testing "Trivial 1-digit cages ▶ 9"
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(is (= [[9]] (killer-sudoku-helper/combinations {:sum 9 :size 1 :exclude []})))))
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(deftest combinations_test_10
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(testing "Cage with sum 45 contains all digits 1:9"
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(is (= [[1 2 3 4 5 6 7 8 9]] (killer-sudoku-helper/combinations {:sum 45 :size 9 :exclude []})))))
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(deftest combinations_test_11
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(testing "Cage with only 1 possible combination"
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(is (= [[1 2 4]] (killer-sudoku-helper/combinations {:sum 7 :size 3 :exclude []})))))
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(deftest combinations_test_12
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(testing "Cage with several combinations"
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(is (= [[1 9] [2 8] [3 7] [4 6]] (killer-sudoku-helper/combinations {:sum 10 :size 2 :exclude []})))))
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(deftest combinations_test_13
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(testing "Cage with several combinations that is restricted"
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(is (= [[2 8] [3 7]] (killer-sudoku-helper/combinations {:sum 10 :size 2 :exclude [1 4]})))))

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