/**
* Comb sort: A variation on bubble sort that dramatically improves performance.
*Source: http://yagni.com/combsort/
*Requirements: Needs to be able to compare elements with <=>, and the [] []= methods should
*be implemented for the container.
*Time Complexity: О(n^2)
*Space Complexity: О(n) total, O(1) auxiliary
*Stable: Yes
*
*@param array $arr Array to be sorted
*@return array
*/
public static function comb_sort($arr)
{
$gap = floor(count($arr) / Sort::$SHRINK_FACTOR);
while ($gap > 0) {
for ($i = 0; $i < count($arr) - $gap; ++$i) {
$arrWithGapsKeys = array();
$arrWithGaps = array();
$loop = true;
$j = $i;
while ($loop) {
if (isset($arr[$j])) {
$arrWithGapsKeys[] = (int) $j;
$arrWithGaps[] = $arr[$j];
$j += $gap;
} else {
$loop = false;
}
}
$arrWithGapsOrdered = Sort::bubble_sort($arrWithGaps);
foreach ($arrWithGapsKeys as $key) {
$arr[$key] = current($arrWithGapsOrdered);
next($arrWithGapsOrdered);
}
}
$gap = floor($gap / Sort::$SHRINK_FACTOR);
}
return $arr;
}
