# 28. 对称的二叉树

[NowCoder](https://www.nowcoder.com/practice/ff05d44dfdb04e1d83bdbdab320efbcb?tpId=13\&tqId=11211\&tPage=1\&rp=1\&ru=/ta/coding-interviews\&qru=/ta/coding-interviews/question-ranking\&from=cyc\_github)

## 题目描述

![](https://cs-notes-1256109796.cos.ap-guangzhou.myqcloud.com/0c12221f-729e-4c22-b0ba-0dfc909f8adf.jpg)\


## 解题思路

```java
boolean isSymmetrical(TreeNode pRoot) {
    if (pRoot == null)
        return true;
    return isSymmetrical(pRoot.left, pRoot.right);
}

boolean isSymmetrical(TreeNode t1, TreeNode t2) {
    if (t1 == null && t2 == null)
        return true;
    if (t1 == null || t2 == null)
        return false;
    if (t1.val != t2.val)
        return false;
    return isSymmetrical(t1.left, t2.right) && isSymmetrical(t1.right, t2.left);
}
```