diff --git a/src/main/java/com/cool/ling_cha_mount/sliding_windows/Num2090.java b/src/main/java/com/cool/ling_cha_mount/sliding_windows/Num2090.java
new file mode 100644
index 0000000..87b9b33
--- /dev/null
+++ b/src/main/java/com/cool/ling_cha_mount/sliding_windows/Num2090.java
@@ -0,0 +1,39 @@
+package com.cool.ling_cha_mount.sliding_windows;
+
+import java.util.Arrays;
+
+/**
+ * Created with IntelliJ IDEA.
+ *
+ * @Author: Cool
+ * @Date: 2024/10/05/16:34
+ * @Description: 2090. 半径为 k 的子数组平均值
+ * DayNumber 1
+ * Hard 2
+ * Level 3
+ * Score 1358
+ */
+public class Num2090 {
+
+    public int[] getAverages(int[] nums, int k) {
+        int[] res=new int[nums.length];
+        Arrays.fill(res,-1);
+        int num=2*k+1;
+        if(nums.length<num){
+            return res;
+        }
+        long sum=0;
+        for(int i=0;i<num;i++){
+            sum+=nums[i];
+        }
+
+        res[k]=(int)(sum/num);
+
+        for(int i=k+1;i+k<nums.length;i++){
+            sum-=nums[i-(k+1)];
+            sum+=nums[i+k];
+            res[i]=(int)(sum/num);
+        }
+        return res;
+    }
+}