diff --git a/README.md b/README.md
index 81bd1e65acdcd9a7a818ec5e7c347b0f2eab5ca9..7fc708797b94a4b39069cf51bbf972b77c6c82cd 100644
--- a/README.md
+++ b/README.md
@@ -1,5 +1,5 @@
 <div align="center">
-<a href="https://github.com/CyC2018/CS-Notes/blob/master/other/download.md">离线阅读版本下载</a>
+<a href="https://github.com/CyC2018/CS-Notes/blob/master/other/download.md"><strong>离线阅读版本下载</strong></a>
 </div>
 
 <br>
diff --git "a/notes/Leetcode \351\242\230\350\247\243 - \344\272\214\345\210\206\346\237\245\346\211\276.md" "b/notes/Leetcode \351\242\230\350\247\243 - \344\272\214\345\210\206\346\237\245\346\211\276.md"
index d5dd007b08d8bed618588ae8bc3d93ee8170e600..d2c64f9765bf03cbea2d147d8e0243574b8d7c6c 100644
--- "a/notes/Leetcode \351\242\230\350\247\243 - \344\272\214\345\210\206\346\237\245\346\211\276.md"	
+++ "b/notes/Leetcode \351\242\230\350\247\243 - \344\272\214\345\210\206\346\237\245\346\211\276.md"	
@@ -257,7 +257,7 @@ public int findMin(int[] nums) {
 
 ## 6. 查找区间
 
-[34. Search for a Range (Medium)](https://leetcode.com/problems/search-for-a-range/description/)
+[34. Find First and Last Position of Element in Sorted Array (Medium)](https://leetcode.com/problems/find-first-and-last-position-of-element-in-sorted-array/)
 
 ```html
 Input: nums = [5,7,7,8,8,10], target = 8
diff --git "a/notes/Leetcode \351\242\230\350\247\243 - \345\210\206\346\262\273.md" "b/notes/Leetcode \351\242\230\350\247\243 - \345\210\206\346\262\273.md"
index cafb3a459180bc6d1b03c165aa85229d2e5a1fbf..71df3d1869b444dcb85ff3419f4c04c128e91756 100644
--- "a/notes/Leetcode \351\242\230\350\247\243 - \345\210\206\346\262\273.md"	
+++ "b/notes/Leetcode \351\242\230\350\247\243 - \345\210\206\346\262\273.md"	
@@ -77,6 +77,9 @@ The above output corresponds to the 5 unique BST's shown below:
 
 ```java
 public List<TreeNode> generateTrees(int n) {
+    if(n < 1){
+        return new LinkedList<TreeNode>();
+    }
     return generateSubtrees(1, n);
 }