PHP冒泡排序-手写

<?php
$a = [1,3,5,2,9,6];
for ($i = 0 ;$i < count($a) ;$i++) {
    for ($j = $i + 1;$j < count($a) ; $j ++) {
        if ($a[$i] > $a[$j]) {
            $tmp = $a[$i];
            $a[$i] = $a[$j];
            $a[$j] = $tmp;
        }
    }
}
print_r($a);

Array
(
    [0] => 1
    [1] => 2
    [2] => 3
    [3] => 5
    [4] => 6
    [5] => 9
)