头晕了，我这个选择排序哪不对啊？

Question

<?php 

//首先，把从1到100之间的数字打断

    $a = range(1,100);
    echo implode(',',$a)."<>";

    shuffle($a);

    echo "<hr>".implode(',',$a)."<hr>";

//然后取出其中十个数字

    for ($i=0; $i <10 ; $i++) 
    {
        $b[$i] = $a[$i];
    }

    echo implode(',',$b)."<hr>";

//使用选择进行排序从小到大

    $length = count($b);

    for ($x=0 ; $x < $length ; $x++) 
    { 
        $temp = 0;
        $min = $b[0];
        $min_index = 0;

        for ($y=$x ; $y < $length; $y++) 
        {
            if ( $min > $b[$y] )
            {
                $min = $b[$y];
                $min_index = $y;
            }
        }
        $temp = $b[$min_index];
        $b[$min_index] = $b[$x];
        $b[$x] = $temp;
    }

    echo implode(',',$b);


 ?>

Answer 1

http://www.gan-ren.com/hr_ttvggdfc.htm