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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,17 @@ | ||
| <?php | ||
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| namespace DataStructures\CompareBinaryTree; | ||
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| class BinaryTreeNode | ||
| { | ||
| public function __construct($value, ?BinaryTreeNode $left = null, BinaryTreeNode $right = null) | ||
| { | ||
| $this->value = $value; | ||
| $this->left = $left; | ||
| $this->right = $right; | ||
| } | ||
|
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| public $value; | ||
| public ?BinaryTreeNode $left; | ||
| public ?BinaryTreeNode $right; | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,35 @@ | ||
| <?php | ||
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| namespace DataStructures\CompareBinaryTree; | ||
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| /** | ||
| * Recurrent comparison of binary trees based on comparison of left and right branches | ||
| * (https://en.wikipedia.org/wiki/Binary_tree). | ||
| * | ||
| * @author Michał Żarnecki https://github.com/rzarno | ||
| */ | ||
| class CompareBinaryTree | ||
| { | ||
| /** | ||
| * compare two binary trees | ||
| * @param BinaryTreeNode|null $a | ||
| * @param BinaryTreeNode|null $b | ||
| * @return bool | ||
| */ | ||
| public function areTreesEqual(?BinaryTreeNode $a, ?BinaryTreeNode $b): bool | ||
| { | ||
| if (! $a && $b || $a && ! $b) { | ||
| return false; | ||
| } | ||
|
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| if (! $a && ! $b) { | ||
| return true; | ||
| } | ||
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| if ($a->value !== $b->value) { | ||
| return false; | ||
| } | ||
| return $this->areTreesEqual($a->left, $b->left) | ||
| && $this->areTreesEqual($a->right, $b->right); | ||
| } | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,43 @@ | ||
| <?php | ||
|
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| namespace DataStructures\InvertBinaryTree; | ||
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| class BinaryTree | ||
| { | ||
| private ?BinaryTree $left = null; | ||
| private ?BinaryTree $right = null; | ||
| private $value; | ||
|
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| public function setLeft(?BinaryTree $left) | ||
| { | ||
| $this->left = $left; | ||
| return $this; | ||
| } | ||
|
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| public function getLeft(): ?BinaryTree | ||
| { | ||
| return $this->left; | ||
| } | ||
|
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| public function setRight(?BinaryTree $right) | ||
| { | ||
| $this->right = $right; | ||
| return $this; | ||
| } | ||
|
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| public function getRight(): ?BinaryTree | ||
| { | ||
| return $this->right; | ||
| } | ||
|
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| public function setValue($value) | ||
| { | ||
| $this->value = $value; | ||
| return $this; | ||
| } | ||
|
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| public function getValue() | ||
| { | ||
| return $this->value; | ||
| } | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,24 @@ | ||
| <?php | ||
|
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| namespace DataStructures\InvertBinaryTree; | ||
|
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| /** | ||
| * Recurrent algorithm to invert binary tree (mirror) | ||
| * (https://medium.com/@kvrware/inverting-binary-tree-b0ff3a5cb0df). | ||
| * | ||
| * @author Michał Żarnecki https://github.com/rzarno | ||
| */ | ||
| class InvertBinaryTree | ||
| { | ||
| public function invert(?BinaryTree $b): void | ||
| { | ||
| if (! $b) { | ||
| return; | ||
| } | ||
| $tmp = $b->getLeft(); | ||
| $b->setLeft($b->getRight()); | ||
| $b->setRight($tmp); | ||
| $this->invert($b->getLeft()); | ||
| $this->invert($b->getRight()); | ||
| } | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,43 @@ | ||
| <?php | ||
|
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| namespace DataStructures\ReverseLinkedList; | ||
|
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| class LinkedListItem | ||
| { | ||
| private ?LinkedListItem $next = null; | ||
| private ?LinkedListItem $prev = null; | ||
| private $value; | ||
|
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| public function setNext(?LinkedListItem $next) | ||
| { | ||
| $this->next = $next; | ||
| return $this; | ||
| } | ||
|
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| public function getNext(): ?LinkedListItem | ||
| { | ||
| return $this->next; | ||
| } | ||
|
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| public function setPrev(?LinkedListItem $prev) | ||
| { | ||
| $this->prev = $prev; | ||
| return $this; | ||
| } | ||
|
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| public function getPrev(): ?LinkedListItem | ||
| { | ||
| return $this->prev; | ||
| } | ||
|
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| public function setValue($value) | ||
| { | ||
| $this->value = $value; | ||
| return $this; | ||
| } | ||
|
|
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| public function getValue() | ||
| { | ||
| return $this->value; | ||
| } | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,28 @@ | ||
| <?php | ||
|
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| namespace DataStructures\ReverseLinkedList; | ||
|
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| /** | ||
| * Reverse linked list | ||
| * (https://en.wikipedia.org/wiki/Linked_list). | ||
| * | ||
| * @author Michał Żarnecki https://github.com/rzarno | ||
| */ | ||
| class ReverseLinkedList | ||
| { | ||
| public function reverse(LinkedListItem $item): LinkedListItem | ||
| { | ||
| $next = $item->getNext(); | ||
| $item->setNext(null); | ||
| while (true) { | ||
| $item->setPrev($next); | ||
| if (! $next) { | ||
| return $item; | ||
| } | ||
| $nextNext = $next->getNext(); | ||
| $next->setNext($item); | ||
| $item = $next; | ||
| $next = $nextNext; | ||
| } | ||
| } | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,43 @@ | ||
| <?php | ||
|
|
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| /** | ||
| * The Dijkstra's algorithm is an algorithm for finding the shortest paths between nodes in a weighted graph. | ||
| * (https://en.wikipedia.org/wiki/Dijkstra%27s_algorithm). | ||
| * | ||
| * @author Michał Żarnecki https://github.com/rzarno | ||
| * @param array $verticesNames An array of vertices names | ||
| * @param GraphEdge[] $edges An array of edges | ||
| * @param string $start The starting vertex | ||
| * @return array An array of shortest paths from $start to all other vertices | ||
| */ | ||
| function dijkstras(array $verticesNames, array $edges, string $start): array | ||
| { | ||
| $vertices = array_combine($verticesNames, array_fill(0, count($verticesNames), PHP_INT_MAX)); | ||
| $visitedNodes = []; | ||
|
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| $nextVertex = $start; | ||
| $vertices[$start] = 0; | ||
| while (count($visitedNodes) < count($verticesNames)) { //continue until all nodes are visited | ||
| foreach ($edges as $edge) { | ||
| if ($edge->start == $nextVertex) { //consider only nodes connected to current one | ||
| $vertices[$edge->end] = min($vertices[$edge->end], $vertices[$nextVertex] + $edge->weight); | ||
| } | ||
| } | ||
|
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| // find vertex with current lowest value to be starting point in next iteration | ||
| $minVertexName = null; | ||
| $minVertexWeight = PHP_INT_MAX; | ||
| foreach ($vertices as $name => $weight) { | ||
| if (in_array($name, $visitedNodes) || $name == $nextVertex) { | ||
| continue; | ||
| } | ||
| if ($weight <= $minVertexWeight) { | ||
| $minVertexName = $name; | ||
| $minVertexWeight = $weight; | ||
| } | ||
| } | ||
| $visitedNodes[] = $nextVertex; | ||
| $nextVertex = $minVertexName; | ||
| } | ||
| return $vertices; | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,8 @@ | ||
| <?php | ||
|
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| class GraphEdge | ||
| { | ||
| public string $start; | ||
| public string $end; | ||
| public int $weight; | ||
| } |
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