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Implemented the ability to calculate every possible combination of a set.
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‎.php_cs‎

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@@ -7,7 +7,7 @@ Copyright © 2019 PHP Experts, Inc.
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Author: Theodore R. Smith <theodore@phpexperts.pro>
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GPG Fingerprint: 4BF8 2613 1C34 87AC D28F 2AD8 EB24 A91D D612 5690
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https://www.phpexperts.pro/
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https://github.com/PHPExpertsInc/Skeleton
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https://github.com/PHPExpertsInc/Combinatorics
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This file is licensed under the MIT License.
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HEADER;

‎README.md‎

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# Combinatorics
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[![TravisCI]()]()
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[![Maintainability]()]()
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[![Test Coverage]()]()
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[![TravisCI](https://travis-ci.org/phpexpertsinc/Combinatorics.svg?branch=master)](https://travis-ci.org/phpexpertsinc/Combinatorics)
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[![Maintainability](https://api.codeclimate.com/v1/badges/cb607de8292ed5b208ae/maintainability)](https://codeclimate.com/github/phpexpertsinc/Combinatorics/maintainability)
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[![Test Coverage](https://api.codeclimate.com/v1/badges/cb607de8292ed5b208ae/test_coverage)](https://codeclimate.com/github/phpexpertsinc/Combinatorics/test_coverage)
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Combinatorics is a PHP Experts, Inc., Project meant for the ease of access of Combinatorics algorithms.
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See https://en.wikipedia.org/wiki/Combinatorics
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### Memory Consumption
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Storing thousands of possibilities can be extremely memory intensive.
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However, this project utilizes PHP Generators and uses only a few kilobytes to calculate and output
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millions of potential combinations (See the **Benchmarks** section below).
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### Generating All Possible Combinations
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What are all the possibilities of A, B, C and D? More than you might think! 64.
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Add two more letters and you've got 1,956 possibilities.
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How many different parking spot orderings can 8 cars occupy on any given day?
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Find out in the **Usage** section below!
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## Installation
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Via Composer
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```
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## Usage
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```php
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$generator = new CombinationsGenerator();
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foreach ($generator->generate($styles) as $combination) {
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// If you can do what you need to do with the combinations here, without immediately storing
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// them into an array, then your memory usage will never exceed the amount needed store one
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// combination.
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}
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```
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You can see real-world usage of this project in the test suite of the
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**Console Painter project**](https://github.com/PHPExpertsInc/ConsolePainter).
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# Use cases
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## Use cases
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## Testing
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phpunit --debug
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```
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Note: It takes over 4 minutes on an Intel i7 to run all of the stress tests.
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Note: It takes over 5 minutes on an Intel i7 to run all of the stress tests.
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## Benchmarks
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```php
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Level 1: Generating combinations for A
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[
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Number of possibilities => 2
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Time (ms) => 0.051975250244141
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Time (s) => 5.1975250244141E-5
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Memory consumed => 0
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Peak Memory (Diff) => 0
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]
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Level 2: Generating combinations for A, B
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[
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Number of possibilities => 4
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Time (ms) => 0.047922134399414
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Time (s) => 4.7922134399414E-5
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Memory consumed => 0
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Peak Memory (Diff) => 0
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]
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Level 3: Generating combinations for A, B, C
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[
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Number of possibilities => 15
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Time (ms) => 0.22578239440918
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Time (s) => 0.00022578239440918
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Memory consumed => 0
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Peak Memory (Diff) => 0
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]
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Level 4: Generating combinations for A, B, C, D
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[
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Number of possibilities => 64
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Time (ms) => 1.0910034179688
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Time (s) => 0.0010910034179688
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Memory consumed => 0
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Peak Memory (Diff) => 0
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]
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Level 5: Generating combinations for A, B, C, D, E
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[
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Number of possibilities => 325
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Time (ms) => 6.5748691558838
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Time (s) => 0.0065748691558838
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Memory consumed => 0
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Peak Memory (Diff) => 0
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]
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Level 6: Generating combinations for A, B, C, D, E, F
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[
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Number of possibilities => 1956
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Time (ms) => 47.721147537231
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Time (s) => 0.047721147537231
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Memory consumed => 0
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Peak Memory (Diff) => 0
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]
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Level 7: Generating combinations for A, B, C, D, E, F, G
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[
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Number of possibilities => 13699
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Time (ms) => 395.29585838318
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Time (s) => 0.39529585838318
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Memory consumed => 0
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Peak Memory (Diff) => 0
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]
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Level 8: Generating combinations for A, B, C, D, E, F, G, H
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[
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Number of possibilities => 109600
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Time (ms) => 3834.4430923462
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Time (s) => 3.8344430923462
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Memory consumed => 0
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Peak Memory (Diff) => 0
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]
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Level 9: Generating combinations for A, B, C, D, E, F, G, H, I
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[
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Number of possibilities => 986409
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Time (ms) => 37884.353876114
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Time (s) => 37.884353876114
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Memory consumed => 320
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Peak Memory (Diff) => 0
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]
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Level 10: Generating combinations for A, B, C, D, E, F, G, H, I, J
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[
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Number of possibilities => 9864100
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Time (ms) => 422606.03785515
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Time (s) => 422.60603785515
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Memory consumed => 0
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Peak Memory (Diff) => 0
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]
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```
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# Contributors
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## Contributors
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[Theodore R. Smith](https://www.phpexperts.pro/]) <theodore@phpexperts.pro>
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GPG Fingerprint: 4BF8 2613 1C34 87AC D28F 2AD8 EB24 A91D D612 5690

‎src/CombinationGenerator.php‎

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<?php declare(strict_types=1);
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/**
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* This file is part of Combinatorics, a PHP Experts, Inc., Project.
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*
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* Copyright © 2019 PHP Experts, Inc.
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* Author: Theodore R. Smith <theodore@phpexperts.pro>
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* GPG Fingerprint: 4BF8 2613 1C34 87AC D28F 2AD8 EB24 A91D D612 5690
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* https://www.phpexperts.pro/
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* https://github.com/PHPExpertsInc/Combinatorics
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*
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* This file is licensed under the MIT License.
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*/
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namespace PHPExperts\Combinatorics;
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class CombinationsGenerator
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{
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/**
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* Taken from https://stackoverflow.com/a/56598845/430062.
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*
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* @param array $list
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*
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* @return \Generator
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*/
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public function generate(array $list): \Generator
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{
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// Generate even partial combinations.
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$list = array_values($list);
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$listCount = count($list);
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for ($a = 0; $a < $listCount; ++$a) {
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yield [$list[$a]];
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}
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if ($listCount > 2) {
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for ($i = 0; $i < count($list); ++$i) {
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$listCopy = $list;
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$entry = array_splice($listCopy, $i, 1);
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foreach ($this->generate($listCopy) as $combination) {
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yield array_merge($entry, $combination);
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}
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}
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} elseif (count($list) > 0) {
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yield $list;
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if (count($list) > 1) {
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yield array_reverse($list);
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}
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}
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}
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}

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