对称的二叉树

题目描述

请实现一个函数，用来判断一颗二叉树是不是对称的。注意，如果一个二叉树同此二叉树的镜像是同样的，定义其为对称的。

public class Solution {

    boolean isSymmetrical(TreeNode pRoot) {

        if (pRoot == null)

            return true;

        return judge(pRoot.left, pRoot.right);

    }

 

    private boolean judge (TreeNode left, TreeNode right) {

        if (left == null)

            return right == null;

        if (right == null)

            return false;

        if (left.val != right.val)

            return false;

        return judge(left.right, right.left) && judge(left.left, right.right);

    }

}