[Leetcode] invalid Ric tree

Problem description:

Given a binary tree, check whether it is a mirror of itself (ie, shortric around its center ).

For example, this binary tree is unsupported Ric:

    1   /   2   2 / \ / 3  4 4  3

But the following is not:

    1   /   2   2   \      3    3

Note:
Bonus points if you cocould solve it both recursively and iteratively.

Confused what"{1, #, 2, 3 }"Means?> Read more on how binary tree is serialized on OJ.

Code:

Recursive Method

public class Symmetric_Tree { //javapublic class TreeNode {      int val;      TreeNode left;      TreeNode right;      TreeNode(int x) { val = x; } }//recursivelypublic boolean isSymmetric(TreeNode root) {      if(root == null)      return true;           return isSymmetricTree(root.left, root.right);          }public boolean isSymmetricTree(TreeNode left, TreeNode right){if(left == null && right == null)return true;if(left == null || right == null ||left.val != right.val)return false;boolean lr = isSymmetricTree(left.left, right.right);boolean rl = isSymmetricTree(left.right, right.left);return lr && rl;}}

[Leetcode] invalid Ric tree