# 27. 二叉树的镜像

[NowCoder](https://www.nowcoder.com/practice/564f4c26aa584921bc75623e48ca3011?tpId=13&tqId=11171&tPage=1&rp=1&ru=/ta/coding-interviews&qru=/ta/coding-interviews/question-ranking&from=cyc_github)

## 题目描述

<div align="center"> <img src="https://cs-notes-1256109796.cos.ap-guangzhou.myqcloud.com/0c12221f-729e-4c22-b0ba-0dfc909f8adf.jpg" width="300"/> </div><br>

## 解题思路

```java
public void Mirror(TreeNode root) {
    if (root == null)
        return;
    swap(root);
    Mirror(root.left);
    Mirror(root.right);
}

private void swap(TreeNode root) {
    TreeNode t = root.left;
    root.left = root.right;
    root.right = t;
}
```