题目： PHP 实现堆排序
描述：
- 堆排序
- 基本思想:
- 堆排序(HeapSort)是一树形选择排序。
- 在排序过程中，将R[l…n]看成是一棵完全二叉树的顺序存储结构，
- 利用完全二叉树中双亲结点和孩子结点之间的内在关系，
- 在当前无序区中选择关键字最大(或最小)的记录。
- 根结点(亦称为堆顶)的关键字是堆里所有结点关键字中最小者的堆称为小根堆。
- 根结点(亦称为堆顶)的关键字是堆里所有结点关键字中最大者，称为大根堆。
function heapSort(array $list){
$length = count($list);
buildHeap($list, $length - 1);
while(--$length){
$temp = $list[0];
$list[0] = $list[$length];
$list[$length] = $temp;
heapAdjust($list, 0, $length);
}
return $list;
}
function buildHeap(array &$list, $num){
for($i = floor(($num - 1) / 2); $i >= 0; $i--){
heapAdjust($list, $i, $num + 1);
}
}
function heapAdjust(array &$list, $i, $num){
if($i > $num / 2){
return ;
}
$key = $i;
$leftChild = $i * 2 + 1;
$rightChild = $i * 2 + 2;
if ($leftChild < $num && $list[$leftChild] > $list[$key]) {
$key = $leftChild;
}
if ($rightChild < $num && $list[$rightChild] > $list[$key]) {
$key = $rightChild;
}
if ($key != $i) {
$val = $list[$i];
$list[$i] = $list[$key];
$list[$key] = $val;
heapAdjust($list, $key, $num);
// heapPrint($list);
}
}
// function heapPrint(array $list){
// echo '<br>';
// echo 'Memory Structure:';
// echo '[ ' . implode(', ', $list) . ' ]';
// echo '<br>';
// echo 'Heap:';
// echo '<br>';
// $nbsp = ' ';
// $length = count($list);
// $level = ceil(sqrt($length));
// //start index
// for($j = 0; $j < $level; $j++){
// $startIndex = pow(2, $j) - 1;
// $endIndex = pow(2, $j) + $startIndex;
// for($i = $startIndex; $i < $endIndex; $i++){
// if($i < $length){
// echo $nbsp;
// echo $list[$i];
// echo $nbsp;
// }
// }
// echo '<br>';
// }
// }
$list = array(3, 6, 2, 4, 10, 1 ,9, 8, 5, 7);
// heapPrint($list);
$result = heapSort($list);
// heapPrint($result);
var_dump($result);
/**
* 分析：
* Memory Structure:[ 3, 6, 2, 4, 10, 1, 9, 8, 5, 7 ]
* Heap:
* 3
* 6 2
* 4 10 1 9
* 8 5 7
*
* Memory Structure:[ 3, 6, 2, 8, 10, 1, 9, 4, 5, 7 ]
* Heap:
* 3
* 6 2
* 8 10 1 9
* 4 5 7
* Memory Structure:[ 3, 6, 9, 8, 10, 1, 2, 4, 5, 7 ]
* Heap:
* 3
* 6 9
* 8 10 1 2
* 4 5 7
* Memory Structure:[ 3, 10, 9, 8, 7, 1, 2, 4, 5, 6 ]
* Heap:
* 3
* 10 9
* 8 7 1 2
* 4 5 6
* Memory Structure:[ 3, 10, 9, 8, 7, 1, 2, 4, 5, 6 ]
* Heap:
* 3
* 10 9
* 8 7 1 2
* 4 5 6
* Memory Structure:[ 10, 8, 9, 5, 7, 1, 2, 4, 3, 6 ]
* Heap:
* 10
* 8 9
* 5 7 1 2
* 4 3 6
* Memory Structure:[ 10, 8, 9, 5, 7, 1, 2, 4, 3, 6 ]
* Heap:
* 10
* 8 9
* 5 7 1 2
* 4 3 6
* Memory Structure:[ 10, 8, 9, 5, 7, 1, 2, 4, 3, 6 ]
* Heap:
* 10
* 8 9
* 5 7 1 2
* 4 3 6
* Memory Structure:[ 9, 8, 6, 5, 7, 1, 2, 4, 3, 10 ]
* Heap:
* 9
* 8 6
* 5 7 1 2
* 4 3 10
* Memory Structure:[ 8, 7, 6, 5, 3, 1, 2, 4, 9, 10 ]
* Heap:
* 8
* 7 6
* 5 3 1 2
* 4 9 10
* Memory Structure:[ 8, 7, 6, 5, 3, 1, 2, 4, 9, 10 ]
* Heap:
* 8
* 7 6
* 5 3 1 2
* 4 9 10
* Memory Structure:[ 7, 5, 6, 4, 3, 1, 2, 8, 9, 10 ]
* Heap:
* 7
* 5 6
* 4 3 1 2
* 8 9 10
* Memory Structure:[ 7, 5, 6, 4, 3, 1, 2, 8, 9, 10 ]
* Heap:
* 7
* 5 6
* 4 3 1 2
* 8 9 10
* Memory Structure:[ 6, 5, 2, 4, 3, 1, 7, 8, 9, 10 ]
* Heap:
* 6
* 5 2
* 4 3 1 7
* 8 9 10
* Memory Structure:[ 5, 4, 2, 1, 3, 6, 7, 8, 9, 10 ]
* Heap:
* 5
* 4 2
* 1 3 6 7
* 8 9 10
* Memory Structure:[ 5, 4, 2, 1, 3, 6, 7, 8, 9, 10 ]
* Heap:
* 5
* 4 2
* 1 3 6 7
* 8 9 10
* Memory Structure:[ 4, 3, 2, 1, 5, 6, 7, 8, 9, 10 ]
* Heap:
* 4
* 3 2
* 1 5 6 7
* 8 9 10
* Memory Structure:[ 3, 1, 2, 4, 5, 6, 7, 8, 9, 10 ]
* Heap:
* 3
* 1 2
* 4 5 6 7
* 8 9 10
* Memory Structure:[ 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 ]
* Heap:
* 1
* 2 3
* 4 5 6 7
* 8 9 10
*/
