PHP bubble sort and quick sort algorithm

This article mainly introduces the PHP bubble sorting and quick sorting algorithms. Interested friends can refer to it. I hope it will be helpful to everyone.

The code is as follows:

$a=array('3','8','1','4','11','7');
print_r($a);
$len = count($a);
//从小到大
for($i=1;$i<$len;$i++)
{
for($j=$len-1;$j>=$i;$j--)
if($a[$j]<$a[$j-1])
{//如果是从大到小的话，只要在这里的判断改成if($b[$j]>$b[$j-1])就可以了
 $x=$a[$j];
 $a[$j]=$a[$j-1];
 $a[$j-1]=$x;
}
}
print_r($a);j
//另一种方法 从小到大
$b=array(&#39;4&#39;,&#39;3&#39;,&#39;8&#39;,&#39;9&#39;,&#39;2&#39;,&#39;1&#39;);
$len=count($b);
for($k=1;$k<$len;$k++)
{
for($j=$len-1,$i=0;$i<$len-$k;$i++,$j--)
if($b[$j]<$b[$j-1]){
//如果是从大到小的话，只要在这里的判断改成if($b[$j]>$b[$j-1])就可以了
 $tmp=$b[$j];
 $b[$j]=$b[$j-1];
 $b[$j-1]=$tmp;
}
print_r($b);
echo "
";
}
//下面的这个执行效率更高
function maopao($arr)
{
 $len = count($arr);
 for($i=1; $i<$len; $i++)//最多做n-1趟排序
 {
 $flag = false;  //本趟排序开始前，交换标志应为假
 for($j=$len-1;$j>=$i;$j--)
 {
  if($arr[$j]<$arr[$j-1])//交换记录
  {//如果是从大到小的话，只要在这里的判断改成if($arr[$j]>$arr[$j-1])就可以了
   $x=$arr[$j];
   $arr[$j]=$arr[$j-1];
   $arr[$j-1]=$x;
   $flag = true;//发生了交换，故将交换标志置为真
  }
 }
 if(! $flag)//本趟排序未发生交换，提前终止算法
 return $arr;  
 }
}
$shuz = array(&#39;2&#39;,&#39;4&#39;,&#39;1&#39;,&#39;8&#39;,&#39;5&#39;);
$bb = maopao($shuz);
print_r($bb);
// 快速排序
function kuaisu($arr){
  $len = count($arr);
  if($len <= 1){
    return $arr;
  }
  $key = $arr[0];
  $left_arr = array();
  $right_arr = array();
  for($i=1; $i<$len;$i++){
    if($arr[$i] <= $key){
      $left_arr[] = $arr[$i];
    }else{
      $right_arr[] = $arr[$i];
    }
  }
  $left_arr = kuaisu($left_arr);
  $right_arr = kuaisu($right_arr);
  return array_merge($left_arr, array($key), $right_arr);
}
$arr = array(23,98,54,2,9,62,34);
print_r(kuaisu($arr));

Summary: The above is the entire content of this article , I hope it can be helpful to everyone’s study.

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