Question

我在从包含实体及其子节点的多维数组构建无序列表时遇到问题。问题是我不想使用递归，因为树可能会变得非常深，递归会在服务器上产生不必要的负载。

这是一个这样的数组的例子（它被简化为包含title和children，实体也可以是对象。

$array = array(
    array('title' => '1', 'children' => array()),
    array('title' => '2', 'children' => array()),
    array('title' => '3', 'children' => array()),
    array('title' => '4', 'children' => array(
        array('title' => '41', 'children' => array()),
        array('title' => '42', 'children' => array()),
        array('title' => '43', 'children' => array()),
        array('title' => '44', 'children' => array(
            array('title' => '441', 'children' => array()),
            array('title' => '442', 'children' => array()),
            array('title' => '443', 'children' => array()),
            array('title' => '444', 'children' => array(
                array('title' => '4441', 'children' => array()),
                array('title' => '4442', 'children' => array()),
                array('title' => '4443', 'children' => array())
            )),
        )),
        array('title' => '45', 'children' => array())
    )),
    array('title' => '5', 'children' => array()),
    array('title' => '6', 'children' => array(
        array('title' => '61', 'children' => array()),
        array('title' => '62', 'children' => array()),
        array('title' => '63', 'children' => array())
    )),
    array('title' => '7', 'children' => array())
);

在这里做一些研究我想出了一个非常接近我想要的解决方案：

<html>
<head></head>
<body>
<ul>
<?php
$stack = $array;
$i = 0;
$counts = array();
while(!empty($stack)) {
    $node = array_shift($stack);
    echo "<li>{$node['title']}";
    if($node['children']) {
        echo "<ul>";
        $counts[] = count($node['children']);
        $node['children'] = array_reverse($node['children']);
        foreach($node['children'] as $ch)
            array_unshift($stack, $ch);
    }
    if(!empty($counts)) {
        end($counts);
        if($counts[$key] == 0) {
            echo "</ul>";
            array_pop($counts);
        } else {
            $counts[$key]--;
        }
    }
    if(!$node['children']) {
        echo "</li>";
    }

    // just to make sure we won't end in infinite loop
    $i++;
    if($i == 50) break;
}
?>
</ul>
</body>
</html>

输出低于 - 正如您所看到的，我遇到的问题只是子树的结束</ul>。 我的问题：我是在思考它还是我是盲目的，没有看到明显的错误？你能否请我推进有限解决方案或给我你自己的解决方案？

输出：

1
2
3
4
- 41
- 42
- 43
- 44
  - 441
  - 442
  - 443
  - 444
    - 4441
    - 4442
    - 4443
  - 45
- 5
- 6
  - 61
  - 62
  - 63
7

Answer 1

这不是对您的代码的修复，但也许它会对您有所帮助：

function helper($input) {
  $input[] = '</ul>';
  $input = array_reverse($input);
  $input[] = '<ul>';

  // output
  while (sizeof($input) > 0) {
    $el = array_pop($input);

    if (!is_array($el)) {
      echo $el; 
    }
    else {
      // add current element
      $input[] = sprintf('<li>%s', $el['title']);

      // add children
      if (sizeof($el['children']) > 0) {
        $input[] = '</ul>';
        $input = array_merge($input, array_reverse($el['children']));
        $input[] = '<ul>';
      }

      // add closing li
      $input[] = '</li>';
    }
  }
}

helper($array);

演示：http://codepad.viper-7.com/qin15V

Answer 2

好的，正如通常所做的那样 - ask for a solution You are solving for hours and immediately You are out with one... - 所以在经过一番小小的放松之后，我还想更多地思考一下这个解决方案：

<html>
<head></head>
<body>
<ul>
<?php
$i = 0;
$counts = array();
while(!empty($stack)) {
    $node = array_shift($stack);
    if(!empty($counts)) {
        while(end($counts) === 0) {
            $key = key($counts);
            echo "</li></ul>";
            array_pop($counts);
        }
        end($counts);
        $key = key($counts);
        if(isset($counts[$key])) {
            $counts[$key]--;
        }
    }
    echo "<li>{$node['title']}";
    if($node['children']) {
        echo "<ul>";
        $counts[] = count($node['children']);
        $node['children'] = array_reverse($node['children']);
        foreach($node['children'] as $ch)
            array_unshift($stack, $ch);
    }
    if(!$node['children']) {
        echo "</li>";
    }


    $i++;
    if($i == 50) break;
}
?>
</ul>
<p>$i = <?php echo $i; ?></p>
</body>
</html>

问题是我错过了另一个while，它应该在树上一直减去$counts值......

我会等待接受我自己的回答，只是有人会发布应该被接受的更好的解决方案，而不是我的不那么整洁的解决方案。

从多维数组构建无序列表而不递归

2 个答案: