mathieuviossat/fibonacci-heap

PHP implementation of the Fibonacci heap

Fibonacci heap

The Fibonacci heap is a heap data structure with the best amortized running time. It was developed by Michael L. Fredman and Robert E. Tarjan in 1984. The running time of Dijkstra's algorithm can be improved to O(|E| + |V| log |V|) by using a Fibonacci heap., _(*1)

Installation

composer require mathieuviossat/fibonacci-heap

{
    "require": {
        "mathieuviossat/fibonacci-heap": "~1.0.0"
    }
}

Example

use MathieuViossat\Util\FibonacciHeap;

$movies = new FibonacciHeap();

$movies->insert(4, 'The Phantom Menace');
$movies->insert(5, 'Attack of the Clones');
$movies->insert(6, 'Revenge of the Sith');
$movies->insert(1, 'A New Hope');
$movies->insert(2, 'The Empire Strikes Back');
$movies->insert(3, 'Return of the Jedi');
$movies->insert(7, 'The Force Awakens');

while ($movie = $movies->extractMin())
    echo $movie->getKey() . ' - ' . $movie->getData() . PHP_EOL;

Methods

minimum() : FibonacciHeapElement

Returns the element with the lowest key, or null if the heap is empty.
Complexity: Θ(1), _(*2)

insert(int|float $key, mixed $data) : FibonacciHeapElement

Inserts $data with the priority $key in the heap and return the element.
Complexity: Θ(1), _(*3)

extractMin() : FibonacciHeapElement

Deletes the element with the lowest priority from the heap and return it.
Amortized complexity: O(log n), _(*4)

decreaseKey(FibonacciHeapElement $element, int|float $key) : void

Replaces $element's key by $key. $key must be lower than the old key.
Amortized complexity: Θ(1), _(*5)

delete(FibonacciHeapElement $element) : void

Deletes $element from the heap.
Amortized complexity: O(log n), _(*6)

merge(FibonacciHeap $other) : void

Merges the both heaps. I recommend to only use one of them after that.
Complexity: Θ(1), _(*7)

isEmpty() : bool

Retuns true if the heap is empty, false otherwise.
Complexity: Θ(1), _(*8)

size() / count() / count($heap) : int

Retuns the number of elements in the heap.
Complexity: Θ(1), _(*9)

clear() : void

Removes all elements from the heap.
Complexity: Θ(1), _(*10)

License

This library is published under The MIT License., _(*11)