php 快速排序算法

function  quickSort($array)
{
    if (count($array) <= 1) {
        return $array;
    }
    $key = $array[0];
    $lefArray = array();
    $rightArray = array();
    for ($i = 1, $size = count($array); $i < $size; $i++) {
        $number = $array[$i];
        if ($number <= $key) {
            $lefArray[] = $number;
        }
        else {
            $rightArray[] = $number;
        }
    }
    $lefArray = quickSort($lefArray);
    $rightArray = quickSort($rightArray);
    return array_merge($rightArray, array($key), $lefArray);
}