PHP implementation method to determine whether a binary tree is symmetrical

This article mainly introduces the method of PHP to judge whether a binary tree is symmetrical, involving the relevant operating skills of PHP recursive binary tree judgment nodes. Friends in need can refer to the following.

The example of this article tells the PHP method to judge whether a binary tree is symmetrical. Symmetrical approach. Share it with everyone for your reference, the details are as follows:

Question

Please implement a function to determine whether a binary tree is symmetrical . Note that a binary tree is defined as symmetric if it is the same as the image of the binary tree.

Solution

Recursively judge both sides of the binary 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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