diff --git a/notes/28. 对称的二叉树.md b/notes/28. 对称的二叉树.md
index 626b6a32..15181506 100644
--- a/notes/28. 对称的二叉树.md	
+++ b/notes/28. 对称的二叉树.md	
@@ -1,6 +1,6 @@
 # 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)
+[Leetcode](https://leetcode.cn/problems/dui-cheng-de-er-cha-shu-lcof/)
 
 ## 题目描述
 
@@ -9,19 +9,19 @@
 ## 解题思路
 
 ```java
-boolean isSymmetrical(TreeNode pRoot) {
-    if (pRoot == null)
+public boolean checkSymmetricTree(TreeNode root) {
+    if (root == null)
         return true;
-    return isSymmetrical(pRoot.left, pRoot.right);
+    return checkSymmetricTree(root.left, root.right);
 }
 
-boolean isSymmetrical(TreeNode t1, TreeNode t2) {
+private boolean checkSymmetricTree(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);
+    return checkSymmetricTree(t1.left, t2.right) && checkSymmetricTree(t1.right, t2.left);
 }
 ```