php实现堆排序

针对堆排序的概念自己百度去，今天没事了用php实现堆排序的算法

 1 abstract class Heap {
 2     protected $elements = array();
 3     protected $n = 0;
 4
 5     public abstract function insert($element);
 6
 7     public function isEmpty() {
 8         return $this->n==0;
 9     }
10
11     public function all(){
12         return $this->elements;
13     }
14
15     /**
16      * Extract the top value of the heap
17      *
18     */
19     public function extract() {
20         $element = $this->elements[1];
21         $this->elements[1] = array_pop($this->elements);
22         $this->n--;
23         $this->siftDown();
24         return $element;
25     }
26
27     /**
28      * Rearranges the heap after an extraction to keep the heap property
29      */
30     protected abstract function siftDown();
31
32     /**
33      * Swap two elements on the elements array
34      *
35      */
36     protected function swap($x,$y) {
37         $tmp = $this->elements[$x];
38         $this->elements[$x] = $this->elements[$y];
39         $this->elements[$y] = $tmp;
40     }
41 }
42 class MinHeap extends Heap {
43
44     public function insert($element) {
45         $this->elements[++$this->n] = $element;
46         for ($i = $this->n; $i > 1 && $this->elements[$i >> 1] > $this->elements[$i]; $i = $i >> 1)
47             $this->swap($i >> 1,$i);
48     }
49     protected function siftDown() {
50         for ($i = 1; ($c = $i * 2) <= $this->n; $i = $c) {
51             //Checks which of the smaller child to compare with the parent
52             if ($c+1 <= $this->n && $this->elements[$c+1] < $this->elements[$c])
53                 $c++;
54             if ($this->elements[$i] < $this->elements[$c])
55                 break;
56             $this->swap($c, $i);
57         }
58     }
59
60 }
61
62 function heapSort($array){
63     $heap=new MinHeap();
64     foreach($array as $val){
65         $heap->insert($val);
66
67     }
68     $arr=array();
69     while(!$heap->isEmpty()){
70         $arr[]=$heap->extract();
71     }
72     return $arr;
73 }
74 $array=array(1,13,8,4,5);
75 $arr=heapSort($array);
76 print_r($arr);