diff --git a/problems/0101.对称二叉树.md b/problems/0101.对称二叉树.md
index 063b5429..31c24fc5 100644
--- a/problems/0101.对称二叉树.md
+++ b/problems/0101.对称二叉树.md
@@ -224,8 +224,8 @@ public:
         st.push(root->left);
         st.push(root->right);
         while (!st.empty()) {
-            TreeNode* leftNode = st.top(); st.pop();
             TreeNode* rightNode = st.top(); st.pop();
+            TreeNode* leftNode = st.top(); st.pop();
             if (!leftNode && !rightNode) {
                 continue;
             }
@@ -950,3 +950,4 @@ public bool IsSymmetric(TreeNode root)
 <a href="https://programmercarl.com/other/kstar.html" target="_blank">
   <img src="../pics/网站星球宣传海报.jpg" width="1000"/>
 </a>
+