php如何实现二叉树的子结构判断（代码）

HasSubtree(treeA,treeB)
    if(treeA->val==treeB->val)//根结点相同
        res=tree1HasTreeB(treeA.treeB)
    if !res
        res=HasSubtree(treeA->left.treeB)//第一层遍历
    if !res
        res=HasSubtree(treeA->right.treeB)//第一层遍历
    return res
tree1HasTreeB(treeA,treeB)
    //顺序不能变
    if treeB==null  //B到底的时候，就是true
        return true
    if treeA==null
        return false//B没到底，A到底了，就是false
    if treeA->val!=treeB->val //A和B的结点没对上
        return false
    //短路语法 ，如果前面的是false，直接返回false,后面不用走
    return tree1HasTreeB(treeA->left,treeB->left)&&tree1HasTreeB(treeA->right,treeB->right)

<?php
class TreeNode{
    public $val;
    public $left = NULL;
    public $right = NULL;
    public function __construct($val){
        $this->val = $val;
    }   
}


//构造两棵树
$node1=new TreeNode(1);
$node2=new TreeNode(2);
$node3=new TreeNode(3);
$node4=new TreeNode(4);
$node5=new TreeNode(5);


$treeA=$node1;
$node1->left=$node2;
$node1->right=$node3;
$node3->left=$node4;
$node3->right=$node5;

//var_dump($treeA);

$node6=new TreeNode(3);
$node7=new TreeNode(4);
$node6->left=$node7;
$treeB=$node6;
//var_dump($treeB);

function HasSubtree($pRoot1,$pRoot2){
        $res=false;
        if($pRoot1==null || $pRoot2==null) return $res;
        if($pRoot1->val==$pRoot2->val) $res=tree1HasTree2($pRoot1,$pRoot2);
        if(!$res) $res=HasSubtree($pRoot1->left,$pRoot2);
        if(!$res) $res=HasSubtree($pRoot1->right,$pRoot2);
        return $res;
}
function tree1HasTree2($treeA,$treeB){
        if($treeB==null) return true;
        if($treeA==null) return false;
        if($treeA->val!=$treeB->val) return false;
        return tree1HasTree2($treeA->left,$treeB->left)&&tree1HasTree2($treeA->right,$treeB->right);
}
var_dump(HasSubtree($treeA,$treeB));