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topological sorting, bitvectors, stack/queue improvement and bug fixes
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‎src/Algorithm/Sorting/TopologicalSort.php‎

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<?php
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/**
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* MIT License
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*
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* Copyright (c) 2018 Dogan Ucar
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in all
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* copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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* SOFTWARE.
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*/
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namespace doganoo\PHPAlgorithms\Algorithm\Sorting;
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use doganoo\PHPAlgorithms\Common\Abstracts\AbstractGraph;
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use doganoo\PHPAlgorithms\Common\Exception\InvalidGraphTypeException;
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use doganoo\PHPAlgorithms\Common\Interfaces\IGraphSortable;
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use doganoo\PHPAlgorithms\Datastructure\Graph\Graph\DirectedGraph;
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use doganoo\PHPAlgorithms\Datastructure\Graph\Graph\Node;
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use doganoo\PHPAlgorithms\Datastructure\Lists\ArrayLists\ArrayList;
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use doganoo\PHPAlgorithms\Datastructure\Stackqueue\Stack;
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/**
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* Class TopologicalSort
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*
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* @package doganoo\PHPAlgorithms\Algorithm\Sorting
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*/
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class TopologicalSort implements IGraphSortable {
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/**
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* @param AbstractGraph $graph
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* @return Stack
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* @throws \doganoo\PHPAlgorithms\common\Exception\InvalidKeyTypeException
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* @throws \doganoo\PHPAlgorithms\common\Exception\UnsupportedKeyTypeException
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* @throws InvalidGraphTypeException
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*/
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public function sort(AbstractGraph $graph): Stack {
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if (!$graph instanceof DirectedGraph) {
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throw new InvalidGraphTypeException("topological sorting is only valid for directed graphs");
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}
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if ($graph->hasCycle()) {
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throw new InvalidGraphTypeException("the graph has a cycle. Topological sorting is only possible for directed acyclic graphs");
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}
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$allNodes = $graph->getNodes();
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$result = new Stack();
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$visited = new ArrayList();
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/*
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* starting with any node, it is first necessary to determine
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* whether the node is already visited. If not, a helper method is
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* called, which has the business logic.
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*/
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/** @var Node $node */
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foreach ($allNodes as $node) {
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/*
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* skip node if it is already visited. Notice
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* that $visited and $result are passed by reference
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*/
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if ($visited->containsValue($node)) continue;
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$this->_sort($node, $result, $visited);
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}
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return $result;
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}
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/**
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* @param Node $node
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* @param Stack $result
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* @param ArrayList $visited
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* @return void
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* @throws InvalidGraphTypeException
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* @throws \doganoo\PHPAlgorithms\common\Exception\InvalidKeyTypeException
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* @throws \doganoo\PHPAlgorithms\common\Exception\UnsupportedKeyTypeException
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*/
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private function _sort(Node $node, Stack &$result, ArrayList &$visited): void {
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$visited->add($node);
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/*
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* continue with the adjacent nodes of $node. The method calls itself
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* recursively until there are no nodes (the node is a leaf). Then,
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* the node is added to the stack (which is passed by reference)
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*/
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/** @var Node $adjacent */
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foreach ($node->getAdjacents() as $adjacent) {
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//skip if already visited
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if ($visited->containsValue($adjacent)) continue;
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//recursive call with the adjacent node of $node
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$this->_sort($adjacent, $result, $visited);
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}
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//add node to result stack
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$result->push($node);
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}
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}

‎src/Algorithm/Various/Permutation.php‎

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@@ -50,18 +50,18 @@ public function stringPermutations(string $string): array {
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$result[] = $string;
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return $result;
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}
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$array = StringUtil::stringToArray($string);
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$result = $this->permute($array, "", $result);
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return $result;
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}
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/**
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* returns all permutations of an given array of objects
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*
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* @param array $objects
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* @param $prefix
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* @param array $result
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* @param array $objects
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* @param $prefix
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* @param array $result
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* @return array
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*/
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private function permute(array $objects, $prefix, array $result) {
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//added to the array
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if (0 === $length) {
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$result[] = $prefix;
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return $result;
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}
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//if the number of elements in the array
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//is greater than 0, there are more elements
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//to build an permutation.
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else {
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//The length is decreased by each recursive function call
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for ($i = 0; $i < $length; $i++) {
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//a new prefix is created. The prefix consists of the
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//actual prefix ("" at the beginning) and the next element
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//in the objects array
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$newPrefix = $prefix . $objects[$i];
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// --------------------------------
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//The length is decreased by each recursive function call
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for ($i = 0; $i < $length; $i++) {
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//new object in order to create the new prefix
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$object = $objects[$i];
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//a new prefix is created. The prefix consists of the
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//actual prefix ("" at the beginning) and the next element
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//in the objects array
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$newPrefix = $prefix . $object;
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//since the ith element in objects is used as a prefix,
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//the remaining objects have to be sliced by exactly this
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//object in order to prevent a reoccurrence of the element in
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//the permutation
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$newObjects = \array_merge(
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\array_slice($objects, 0, $i),
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\array_slice($objects, $i + 1)
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);
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//since the ith element in objects is used as a prefix,
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//the remaining objects have to be sliced by exactly this
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//object in order to prevent a reoccurrence of the element in
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//the permutation
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$newObjects = \array_merge(
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\array_slice($objects, 0, $i),
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\array_slice($objects, $i + 1)
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);
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//call the permute method with the new prefix and objects
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$result = $this->permute($newObjects, $newPrefix, $result);
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}
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//call the permute method with the new prefix and objects
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$result = $this->permute($newObjects, $newPrefix, $result);
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}
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return $result;
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}

‎src/Common/Abstracts/AbstractSet.php‎ renamed to ‎src/Common/Abstracts/AbstractISet.php‎

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namespace doganoo\PHPAlgorithms\Common\Abstracts;
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use doganoo\PHPAlgorithms\Common\Interfaces\Set;
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use doganoo\PHPAlgorithms\Common\Interfaces\ISet;
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/**
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* Class AbstractSet
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*
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* @package doganoo\PHPAlgorithms\Common\Abstracts
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*/
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abstract class AbstractSet implements Set {
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abstract class AbstractISet implements ISet {
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/**
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* Compares the specified object with this set for equality.
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*

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