PHP method to determine whether a binary tree is symmetrical

This article mainly introduces the method of judging whether a binary tree is symmetrical in PHP, involving phprecursionrelated operating techniques for judging nodes in a binary tree. Friends who are grateful to PHP can refer to this article

The example of this article describes the method of PHP to determine whether a binary tree is symmetrical. Share it with everyone for your reference, as follows:

Question

Please implement a function to determine a Is this binary tree 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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