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Add zebra-puzzle (#125)
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‎config.json‎

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"practices": [],
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"prerequisites": [],
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"difficulty": 8
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},
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{
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"slug": "zebra-puzzle",
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"name": "Zebra Puzzle",
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"uuid": "71d0556e-4301-47e7-80c2-d3d215127746",
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"practices": [],
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"prerequisites": [],
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"difficulty": 8
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}
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]
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},

‎exercises/practice/zebra-puzzle/.busted‎

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return {
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default = {
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ROOT = { '.' }
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}
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}

‎exercises/practice/zebra-puzzle/.docs/instructions.md‎

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# Instructions
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Your task is to solve the Zebra Puzzle to find the answer to these two questions:
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- Which of the residents drinks water?
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- Who owns the zebra?
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## Puzzle
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The following 15 statements are all known to be true:
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1. There are five houses.
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2. The Englishman lives in the red house.
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3. The Spaniard owns the dog.
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4. The person in the green house drinks coffee.
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5. The Ukrainian drinks tea.
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6. The green house is immediately to the right of the ivory house.
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7. The snail owner likes to go dancing.
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8. The person in the yellow house is a painter.
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9. The person in the middle house drinks milk.
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10. The Norwegian lives in the first house.
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11. The person who enjoys reading lives in the house next to the person with the fox.
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12. The painter's house is next to the house with the horse.
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13. The person who plays football drinks orange juice.
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14. The Japanese person plays chess.
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15. The Norwegian lives next to the blue house.
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Additionally, each of the five houses is painted a different color, and their inhabitants are of different national extractions, own different pets, drink different beverages and engage in different hobbies.
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~~~~exercism/note
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There are 24 billion (5!⁵ = 24,883,200,000) possible solutions, so try ruling out as many solutions as possible.
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~~~~

‎exercises/practice/zebra-puzzle/.docs/introduction.md‎

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# Introduction
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The Zebra Puzzle is a famous logic puzzle in which there are five houses, each painted a different color.
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The houses have different inhabitants, who have different nationalities, own different pets, drink different beverages and enjoy different hobbies.
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To help you solve the puzzle, you're given 15 statements describing the solution.
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However, only by combining the information in _all_ statements will you be able to find the solution to the puzzle.
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~~~~exercism/note
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The Zebra Puzzle is a [Constraint satisfaction problem (CSP)][constraint-satisfaction-problem].
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In such a problem, you have a set of possible values and a set of constraints that limit which values are valid.
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Another well-known CSP is Sudoku.
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[constraint-satisfaction-problem]: https://en.wikipedia.org/wiki/Constraint_satisfaction_problem
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~~~~

‎exercises/practice/zebra-puzzle/.meta/config.json‎

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{
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"authors": [
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"glennj"
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],
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"files": {
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"solution": [
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"zebra_puzzle.moon"
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],
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"test": [
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"zebra_puzzle_spec.moon"
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],
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"example": [
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".meta/example.moon"
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]
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},
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"blurb": "Solve the zebra puzzle.",
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"source": "Wikipedia",
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"source_url": "https://en.wikipedia.org/wiki/Zebra_Puzzle"
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}

‎exercises/practice/zebra-puzzle/.meta/example.moon‎

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permute = require 'pl.permute' -- https://luarocks.org/modules/tieske/penlight
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toTheRightOf = (a, b) -> a == b + 1
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nextTo = (a, b) -> toTheRightOf(a, b) or toTheRightOf(b, a)
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FIRST = 1
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MIDDLE = 3
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-- 1. There are five houses.
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-- 2. The Englishman lives in the red house.
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-- 3. The Spaniard owns the dog.
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-- 4. The person in the green house drinks coffee.
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-- 5. The Ukrainian drinks tea.
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-- 6. The green house is immediately to the right of the ivory house.
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-- 7. The snail owner likes to go dancing.
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-- 8. The person in the yellow house is a painter.
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-- 9. The person in the middle house drinks milk.
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-- 10. The Norwegian lives in the first house.
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-- 11. The person who enjoys reading lives in the house next to the person with the fox.
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-- 12. The painter's house is next to the house with the horse.
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-- 13. The person who plays football drinks orange juice.
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-- 14. The Japanese person plays chess.
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-- 15. The Norwegian lives next to the blue house.
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solve = ->
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-- solve for colours
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for p1 in permute.order_iter {1,2,3,4,5}
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{red, green, ivory, yellow, blue} = p1
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-- clue 6
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if toTheRightOf green, ivory
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-- solve for nationalities
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for p2 in permute.order_iter {1,2,3,4,5}
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{english, spanish, ukrainian, norwegian, japanese} = p2
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-- clues 2, 10, 15
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if english == red and norwegian == FIRST and nextTo norwegian, blue
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nationalities = {
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[english]: 'EnglishMan'
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[spanish]: 'Spaniard'
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[ukrainian]: 'Ukrainian'
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[norwegian]: 'Norwegian'
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[japanese]: 'Japanese'
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}
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-- solve for beverages
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for p3 in permute.order_iter {1,2,3,4,5}
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{coffee, tea, milk, orangeJuice, water} = p3
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-- clues 4, 5, 9
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if coffee == green and ukrainian == tea and milk == MIDDLE
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-- solve for hobbies
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for p4 in permute.order_iter {1,2,3,4,5}
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{dancing, painting, reading, football, chess} = p4
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-- clues 8, 13, 14
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if painting == yellow and football == orangeJuice and japanese == chess
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-- solve for pets
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for p5 in permute.order_iter {1,2,3,4,5}
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{dog, snails, fox, horse, zebra} = p5
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-- clues 3, 7, 11, 12
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if spanish == dog and dancing == snails and nextTo(reading, fox) and nextTo painting, horse
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return {
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waterDrinker: nationalities[water]
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zebraOwner: nationalities[zebra]
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}
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return waterDrinker: '?', zebraOwner: '?'
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SOLUTION = solve!
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{
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drinksWater: -> SOLUTION.waterDrinker
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ownsZebra: -> SOLUTION.zebraOwner
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}

‎exercises/practice/zebra-puzzle/.meta/spec_generator.moon‎

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{
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module_imports: {'drinksWater', 'ownsZebra'},
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generate_test: (case, level) ->
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lines = {
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"assert.are.equal #{quote case.expected}, #{case.property}!"
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}
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table.concat [indent line, level for line in *lines], '\n'
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}

‎exercises/practice/zebra-puzzle/.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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[16efb4e4-8ad7-4d5e-ba96-e5537b66fd42]
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description = "resident who drinks water"
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[084d5b8b-24e2-40e6-b008-c800da8cd257]
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description = "resident who owns zebra"

‎exercises/practice/zebra-puzzle/zebra_puzzle.moon‎

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{
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drinksWater: ->
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error 'Implement me'
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ownsZebra: ->
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error 'Implement me'
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}

‎exercises/practice/zebra-puzzle/zebra_puzzle_spec.moon‎

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import drinksWater, ownsZebra from require 'zebra_puzzle'
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describe 'zebra-puzzle', ->
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it 'resident who drinks water', ->
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assert.are.equal 'Norwegian', drinksWater!
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pending 'resident who owns zebra', ->
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assert.are.equal 'Japanese', ownsZebra!

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