/**
* Heap sort: Uses a heap (implemented by the Containers module) to sort the collection.
* Requirements: Needs to be able to compare elements with <=>
* Time Complexity: О(n^2)
* Space Complexity: О(n) total, O(1) auxiliary
* Stable: Yes
* @param array $array Array to be sorted
* @return array
*/
public static function heap_sort(&$array)
{
//This will heapify the array
$init = (int) floor((count($array) - 1) / 2);
for ($i = $init; $i >= 0; $i--) {
$count = count($array) - 1;
Sort::build_heap($array, $i, $count);
}
//swaping of nodes
for ($i = count($array) - 1; $i >= 1; $i--) {
$tmp_var = $array[0];
$array[0] = $array[$i];
$array[$i] = $tmp_var;
Sort::build_heap($array, 0, $i - 1);
}
return $array;
}
