diff --git a/docs/notes/Leetcode 题解.md b/docs/notes/Leetcode 题解.md
index 78fcf803..f60ed174 100644
--- a/docs/notes/Leetcode 题解.md	
+++ b/docs/notes/Leetcode 题解.md	
@@ -403,12 +403,10 @@ public List<Integer> topKFrequent(int[] nums, int k) {
     }
     List<Integer> topK = new ArrayList<>();
     for (int i = buckets.length - 1; i >= 0 && topK.size() < k; i--) {
-        if (buckets[i] != null) {
-            if (buckets[i].size() <= (k - topK.size())) {
-                topK.addAll(buckets[i]);
-            } else {
-                topK.addAll(buckets[i].subList(0, k - topK.size()));
-            }
+        if (buckets[i].size() <= (k - topK.size())) {
+            topK.addAll(buckets[i]);
+        } else {
+            topK.addAll(buckets[i].subList(0, k - topK.size()));
         }
     }
     return topK;
diff --git a/docs/notes/pics/cb5d2258-a60e-4364-94a7-3429a3064554_200.png b/docs/notes/pics/cb5d2258-a60e-4364-94a7-3429a3064554_200.png
new file mode 100644
index 00000000..7a7c702d
Binary files /dev/null and b/docs/notes/pics/cb5d2258-a60e-4364-94a7-3429a3064554_200.png differ
diff --git a/docs/notes/算法.md b/docs/notes/算法.md
index fa85797c..c7ab83c9 100644
--- a/docs/notes/算法.md
+++ b/docs/notes/算法.md
@@ -382,7 +382,7 @@ public class Insertion<T extends Comparable<T>> extends Sort<T> {
 
 希尔排序使用插入排序对间隔 h 的序列进行排序。通过不断减小 h，最后令 h=1，就可以使得整个数组是有序的。
 
-<div align="center"> <img src="pics/1_200.png"/> </div><br>
+<div align="center"> <img src="pics/cb5d2258-a60e-4364-94a7-3429a3064554_200.png"/> </div><br>
 
 ```java
 public class Shell<T extends Comparable<T>> extends Sort<T> {
diff --git a/docs/pics/cb5d2258-a60e-4364-94a7-3429a3064554_200.png b/docs/pics/cb5d2258-a60e-4364-94a7-3429a3064554_200.png
new file mode 100644
index 00000000..7a7c702d
Binary files /dev/null and b/docs/pics/cb5d2258-a60e-4364-94a7-3429a3064554_200.png differ