leetcode -- Symmetric Tree

转载于 2017-12-25 16:53:00 发布 · 47 阅读

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原文链接：https://my.oschina.net/u/1447519/blog/1594666

文章标签：

#python

本文介绍了一种检查二叉树是否为对称的方法。即判断一棵二叉树是否与其镜像相同。文章提供了一个递归解决方案，通过比较二叉树的左子树和右子树来实现这一目标。

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2019独角兽企业重金招聘Python工程师标准>>>

Symmetric Tree

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

For example, this binary tree [1,2,2,3,4,4,3] is symmetric:

But the following [1,2,2,null,3,null,3] is not:

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

recursive method

class Solution {
    public boolean isSymmetric(TreeNode root) {
        if(root==null)
            return true;
        else{
            return sysmmetric(root.left, root.right);
        }
    }
    
    public boolean sysmmetric(TreeNode left, TreeNode right){
        if(left==null || right == null){
            return left==right;
        }
        if(left.val != right.val){
            return false;
        }
        return sysmmetric(left.left, right.right) && sysmmetric(left.right, right.left);
    }
}

转载于:https://my.oschina.net/u/1447519/blog/1594666