php怎么实现二叉树的存储

php如何实现二叉树的存储？

就像上面图片里面所画的一样，我怎么把那一串数字用二叉树存起来？用php实现。
求大神帮忙呀！！！！
==========初学二叉树
------解决方案--------------------
这个很简单

class node{

   public var $per;

   public var $lNode;

   public var $rNode;



   function test1(){

   }



   function test2(){

   }

}

由于php是弱类型语言，你只要清楚$lNode和$rNode的类型是node,赋值时一定要把node类型的左右节点赋给对应的就可以了。

$node0=new node();

$node0->per = 49;

$node1=new node();

$node1->per = 20;

$node2=new node();

$node2->per = 29;

$node0->lNode = $node1;

$node0->rNode = $node2;

------解决方案--------------------
这样写

<br />
<?php<br />
$s = '4 6 8 9 10 12';<br />
foreach(explode(' ', $s) as $k=>$v) { //初始化<br />
  $t[] = array('w' => $v, 'v' => $v); //用值作为权重<br />
}<br />
HuffmanTree($t);<br />
echo DLR($t), PHP_EOL;<br />
<br />
/* 哈夫曼算法 */<br />
function HuffmanTree(&$F) {<br />
  while(count($F) > 1) {<br />
    $r = array();<br />
    foreach($F as $item) $r[] = $item['w'];<br />
    array_multisort($r, $F);<br />
    $t = array('w' => $F[0]['w']+$F[1]['w'], 'l' => $F[0], 'r' => $F[1]);<br />
    unset($F[0]);<br />
    unset($F[1]);<br />
    $F[] = $t;<br />
  }<br />
  $F = current($F);<br />
}<br />
/* 前序遍历 */<br />
function DLR($F, $deep=0) {<br />
  echo str_repeat("   ", $deep) .'+- ' . $F['w'] . PHP_EOL;//打印权重<br />
  if(isset($F['l'])) DLR($F['l'], $deep+1);<br />
  if(isset($F['r'])) DLR($F['r'], $deep+1);<br />
}<br />
</pre><br />
<br />
+- 49<br />
   +- 20<br />
      +- 10<br />
      +- 10<br />
         +- 4<br />
         +- 6<br />
   +- 29<br />
      +- 12<br />
      +- 17<br />
         +- 8<br />
         +- 9<br />
<br />   </div>

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