diff --git a/notes/剑指 offer 题解.md b/notes/剑指 offer 题解.md
index c0c5412f..5dd25159 100644
--- a/notes/剑指 offer 题解.md	
+++ b/notes/剑指 offer 题解.md	
@@ -411,6 +411,9 @@ Stack<Integer> in = new Stack<Integer>();
 Stack<Integer> out = new Stack<Integer>();
 
 public void push(int node) {
+    if (in.isEmpty())
+        while (!out.isEmpty())
+            in.push(out.pop());
     in.push(node);
 }