diff --git a/src/main/java/com/cool/hot100/binary_tree/Num105.java b/src/main/java/com/cool/hot100/binary_tree/Num105.java
index 59f8868..7f4dccf 100644
--- a/src/main/java/com/cool/hot100/binary_tree/Num105.java
+++ b/src/main/java/com/cool/hot100/binary_tree/Num105.java
@@ -30,7 +30,6 @@ public class Num105 {
         TreeNode node = new TreeNode(preorder[indexInPre]);
         Integer headInIn = map.get(preorder[indexInPre]);
         int leftLength = headInIn - startInIn;
-        int rightLength = endInIn - headInIn;
         node.left = buildTree(preorder,indexInPre+1,startInIn,headInIn-1);
         node.right=buildTree(preorder,indexInPre+leftLength+1,headInIn+1,endInIn);
         return node;