PHP realizes the method of judging whether the binary tree is symmetrical or not

In this paper, an example is given to describe the method of judging whether a 2-tree is symmetrical by PHP. Share it for your reference, as follows:

Problem

Please implement a function to judge whether a 2-tree is symmetric. Note that if a binary tree is the same as the image of this binary tree, it is defined as symmetric.

Problem solution

Recursively judge both sides of a 2-tree.

Implementation code:

<?php
/*class TreeNode{
 var $val;
 var $left = NULL;
 var $right = NULL;
 function __construct($val){
  $this->val = $val;
 }
}*/
function isSymmetrical($pRoot)
{
 if($pRoot==null) return true;
 return compare($pRoot->left,$pRoot->right);
}
function compare($root1,$root2){
 if($root1==null&&$root2==null) return true;
 if($root1==null||$root2==null) return false;
 if($root1->val!=$root2->val) return false;
 return compare($root1->left,$root2->right)&&compare($root1->right,$root2->left);
}

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