/**
* 递归法实现的快速排序
* @param $seq
* @return array
*/
function quicksort($seq)
{
if (count($seq) > 1) {
$k = $seq[0];
$x = array();
$y = array();
$_size = count($seq); //do not use count($seq) in loop for.
for ($i = 1; $i < $_size; $i++) {
if ($seq[$i] <= $k) {
$x[] = $seq[$i];
} else {
$y[] = $seq[$i];
}
}
$x = quicksort($x);
$y = quicksort($y);
return array_merge($x,array($k),$y);
} else {
return $seq;
}
}
/**用迭代实现
* @param $seq
* @return array
*/
function quicksortX(&$seq)
{
$stack = array($seq);
$sort = array();
while ($stack) {
$arr = array_pop($stack);
if(count($arr) <= 1){
if (count($arr) == 1) {
$sort[] = &$arr[0];
}
continue;
}
$k = $arr[0];
$x = array();
$y = array();
$_size = count($arr);
for ($i = 1; $i < $_size; $i++) {
if ($arr[$i] <= $k) {
$x[] = &$arr[$i];
} else {
$y[] = &$arr[$i];
}
}
!empty($y) && array_push($stack,$y);
array_push($stack,array($arr[0]));
!empty($x) && array_push($stack,$x);
}
return $sort;
}
//$testArr = array(5545,5,6,7675,100,9,233,566,789,456,23,55,7,4,343,564,45657,8,998,34,6433,67,6766,2,42,25634,34343,3,454,65,6678,57,5455);
for($i=0;$i<20;$i++){
$testArr[]=mt_rand(0,10000);
}
//var_dump($testArr);
echo count($testArr).'<br>';
$start=microtime();
echo count(quicksort($testArr)).'<br>';
echo microtime()-$start.'<br>';
var_dump(quicksort($testArr));
echo '------------------------------------------------------------------------<br>';
echo count($testArr).'<br>';
$start=microtime();
echo count(quicksortX($testArr)).'<br>';
echo microtime()-$start.'<br>';
var_dump(quicksortX($testArr));
