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Add Zebra Puzzle Exercise (#623)
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‎config.json

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"practices": [],
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"prerequisites": [],
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"difficulty": 6
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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": "8a87919b-3bd0-4fc8-9774-daecd148de42",
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"practices": [],
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"prerequisites": [],
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"difficulty": 7
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}
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]
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},

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

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# Instructions
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Solve the zebra puzzle.
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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. Coffee is drunk in the green house.
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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 Old Gold smoker owns snails.
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8. Kools are smoked in the yellow house.
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9. Milk is drunk in the middle house.
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10. The Norwegian lives in the first house.
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11. The man who smokes Chesterfields lives in the house next to the man with the fox.
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12. Kools are smoked in the house next to the house where the horse is kept.
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13. The Lucky Strike smoker drinks orange juice.
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14. The Japanese smokes Parliaments.
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15. The Norwegian lives next to the blue house.
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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 smoke different brands of cigarettes.
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Which of the residents drinks water?
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Who owns the zebra?

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

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{
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"authors": [
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"tomasnorre"
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],
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"files": {
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"solution": [
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"ZebraPuzzle.php"
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],
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"test": [
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"ZebraPuzzleTest.php"
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],
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"example": [
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".meta/example.php"
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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.php

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<?php
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/*
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* By adding type hints and enabling strict type checking, code can become
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* easier to read, self-documenting and reduce the number of potential bugs.
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* By default, type declarations are non-strict, which means they will attempt
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* to change the original type to match the type specified by the
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* type-declaration.
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*
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* In other words, if you pass a string to a function requiring a float,
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* it will attempt to convert the string value to a float.
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*
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* To enable strict mode, a single declare directive must be placed at the top
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* of the file.
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* This means that the strictness of typing is configured on a per-file basis.
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* This directive not only affects the type declarations of parameters, but also
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* a function's return type.
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*
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* For more info review the Concept on strict type checking in the PHP track
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* <link>.
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*
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* To disable strict typing, comment out the directive below.
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*/
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declare(strict_types=1);
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class ZebraPuzzle
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{
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private $waterDrinker = '';
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private $zebraOwner = '';
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private const FIRST = 1;
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private const MIDDLE = 3;
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private $red = 0;
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private $green = 0;
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private $ivory = 0;
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private $yellow = 0;
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private $blue = 0;
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private $englishman = 0;
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private $spaniard = 0;
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private $ukrainian = 0;
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private $japanese = 0;
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private $norwegian = 0;
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private $coffee = 0;
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private $tea = 0;
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private $milk = 0;
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private $orangeJuice = 0;
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private $water = 0;
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private $oldGold = 0;
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private $kools = 0;
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private $chesterfields = 0;
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private $luckyStrike = 0;
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private $parliaments = 0;
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private $dog = 0;
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private $snails = 0;
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private $fox = 0;
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private $horse = 0;
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private $zebra = 0;
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private $nationalityNames = [];
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private $possiblePermutations;
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public function __construct()
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{
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$this->possiblePermutations = $this->permuteValues([1, 2, 3, 4, 5]);
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$this->solve();
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}
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public function waterDrinker(): string
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{
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return $this->waterDrinker;
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}
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public function zebraOwner(): string
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{
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return $this->zebraOwner;
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}
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private function permuteValues(array $array): array
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{
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$result = [];
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$length = count($array);
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if ($length === 0) {
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return [[]];
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}
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foreach ($array as $index => $value) {
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$rest = $this->permuteValues(array_merge(array_slice($array, 0, $index), array_slice($array, $index + 1)));
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if (empty($rest)) {
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$result[] = [$value];
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} else {
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foreach ($rest as $r) {
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$result[] = array_merge([$value], $r);
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}
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}
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}
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return $result;
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}
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private function isRightOf($houseA, $houseB): bool
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{
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return $houseA - 1 === $houseB;
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}
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private function nextTo($houseA, $houseB): bool
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{
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return $this->isRightOf($houseA, $houseB) || $this->isRightOf($houseB, $houseA);
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}
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private function solve(): void
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{
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foreach ($this->possiblePermutations as $permutation) {
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$this->solveHouseColors($permutation);
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}
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}
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private function solveHouseColors($permutation): void
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{
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$this->red = $permutation[0];
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$this->green = $permutation[1];
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$this->ivory = $permutation[2];
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$this->yellow = $permutation[3];
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$this->blue = $permutation[4];
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if ($this->isRightOf($this->green, $this->ivory)) { // Clue #6
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foreach ($this->possiblePermutations as $perm) {
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$this->solveNationalities($perm);
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}
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}
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}
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private function solveNationalities($permutation): void
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{
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$this->englishman = $permutation[0];
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$this->spaniard = $permutation[1];
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$this->ukrainian = $permutation[2];
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$this->japanese = $permutation[3];
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$this->norwegian = $permutation[4];
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if (
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$this->red === $this->englishman && // Clue #2
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$this->norwegian === self::FIRST && // Clue #10
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$this->nextTo($this->norwegian, $this->blue) // Clue #15
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) {
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$this->nationalityNames[$this->englishman] = 'Englishman';
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$this->nationalityNames[$this->spaniard] = 'Spaniard';
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$this->nationalityNames[$this->ukrainian] = 'Ukrainian';
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$this->nationalityNames[$this->japanese] = 'Japanese';
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$this->nationalityNames[$this->norwegian] = 'Norwegian';
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foreach ($this->possiblePermutations as $perm) {
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$this->solveBeverages($perm);
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}
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}
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}
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private function solveBeverages($permutation): void
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{
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$this->coffee = $permutation[0];
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$this->tea = $permutation[1];
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$this->milk = $permutation[2];
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$this->orangeJuice = $permutation[3];
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$this->water = $permutation[4];
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if (
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$this->coffee === $this->green && // Clue #4
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$this->ukrainian === $this->tea && // Clue #5
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$this->milk === self::MIDDLE // Clue #9
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) {
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foreach ($this->possiblePermutations as $perm) {
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$this->solveCigars($perm);
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}
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}
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}
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private function solveCigars($permutation): void
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{
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$this->oldGold = $permutation[0];
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$this->kools = $permutation[1];
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$this->chesterfields = $permutation[2];
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$this->luckyStrike = $permutation[3];
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$this->parliaments = $permutation[4];
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if (
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$this->kools === $this->yellow && // Clue #8
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$this->luckyStrike === $this->orangeJuice && // Clue #13
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$this->japanese === $this->parliaments // Clue #14
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) {
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foreach ($this->possiblePermutations as $perm) {
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$this->solvePets($perm);
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}
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}
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}
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private function solvePets($permutation): void
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{
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$this->dog = $permutation[0];
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$this->snails = $permutation[1];
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$this->fox = $permutation[2];
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$this->horse = $permutation[3];
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$this->zebra = $permutation[4];
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if (
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$this->spaniard === $this->dog && // Clue #3
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$this->oldGold === $this->snails && // Clue #7
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$this->nextTo($this->chesterfields, $this->fox) && // Clue #11
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$this->nextTo($this->kools, $this->horse) // Clue #12
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) {
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$this->waterDrinker = $this->nationalityNames[$this->water];
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$this->zebraOwner = $this->nationalityNames[$this->zebra];
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}
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}
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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/ZebraPuzzle.php

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<?php
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/*
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* By adding type hints and enabling strict type checking, code can become
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* easier to read, self-documenting and reduce the number of potential bugs.
6+
* By default, type declarations are non-strict, which means they will attempt
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* to change the original type to match the type specified by the
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* type-declaration.
9+
*
10+
* In other words, if you pass a string to a function requiring a float,
11+
* it will attempt to convert the string value to a float.
12+
*
13+
* To enable strict mode, a single declare directive must be placed at the top
14+
* of the file.
15+
* This means that the strictness of typing is configured on a per-file basis.
16+
* This directive not only affects the type declarations of parameters, but also
17+
* a function's return type.
18+
*
19+
* For more info review the Concept on strict type checking in the PHP track
20+
* <link>.
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*
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* To disable strict typing, comment out the directive below.
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*/
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declare(strict_types=1);
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class ZebraPuzzle
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{
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public function waterDrinker(): string
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{
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throw new \BadMethodCallException(sprintf('Implement the %s method', __FUNCTION__));
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}
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public function zebraOwner(): string
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{
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throw new \BadMethodCallException(sprintf('Implement the %s method', __FUNCTION__));
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}
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}

‎exercises/practice/zebra-puzzle/ZebraPuzzleTest.php

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<?php
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/*
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* By adding type hints and enabling strict type checking, code can become
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* easier to read, self-documenting and reduce the number of potential bugs.
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* By default, type declarations are non-strict, which means they will attempt
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* to change the original type to match the type specified by the
8+
* type-declaration.
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*
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* In other words, if you pass a string to a function requiring a float,
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* it will attempt to convert the string value to a float.
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*
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* To enable strict mode, a single declare directive must be placed at the top
14+
* of the file.
15+
* This means that the strictness of typing is configured on a per-file basis.
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* This directive not only affects the type declarations of parameters, but also
17+
* a function's return type.
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*
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* For more info review the Concept on strict type checking in the PHP track
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* <link>.
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*
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* To disable strict typing, comment out the directive below.
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*/
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declare(strict_types=1);
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class ZebraPuzzleTest extends PHPUnit\Framework\TestCase
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{
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private ZebraPuzzle $zebraPuzzle;
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public static function setUpBeforeClass(): void
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{
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require_once 'ZebraPuzzle.php';
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}
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public function setUp(): void
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{
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$this->zebraPuzzle = new ZebraPuzzle();
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}
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/**
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* uuid: 16efb4e4-8ad7-4d5e-ba96-e5537b66fd42
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*/
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public function testResidentWhoDrinksWater(): void
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{
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$this->assertEquals('Norwegian', $this->zebraPuzzle->waterDrinker());
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}
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/**
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* uuid: 084d5b8b-24e2-40e6-b008-c800da8cd257
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*/
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public function testResidentWhoOwnsZebra(): void
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{
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$this->assertEquals('Japanese', $this->zebraPuzzle->zebraOwner());
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}
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}

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