Display child pages in columns

<?php
global $wp_query;

if( empty($wp_query->post->post_parent) ) {
$parent = $wp_query->post->ID;
} else {
$parent = $wp_query->post->post_parent;
} ?>
<?php if(wp_list_pages("title_li=&child_of=$parent&echo=0" )): ?>

<?php
    echo=0 $pageArray = explode("</li>",wp_list_pages('title_li=&child_of=$parent'));
    $pageCount = count($pageArray) - 1;
    $pageColumns = round($pageCount / 3);
    $twoColumns = round($pageColumns + $pageColumns);

        for ($i=0;$i<$pageCount;$i++) {
        if ($i<$pageColumns){
            $pageLeft = $pageLeft.''.$pageArray[$i].'</li>';
        }
            elseif ($i<$twoColumns) {
            $pageMiddle = $pageMiddle.''.$pageArray[$i].'</li>';
        }
        elseif ($i>=$twoColumns) {
            $pageRight = $pageRight.''.$pageArray[$i].'</li>';
        }
     };
 ?>

<ul class="left">
    <?php echo $pageLeft; ?>
</ul>
<ul class="middle">
    <?php echo $pageMiddle; ?>
</ul>
<ul class="right">
    <?php echo $pageRight; ?>
</ul>