diff --git a/src/main/java/com/cool/ling_cha_mount/sliding_windows/Num643.java b/src/main/java/com/cool/ling_cha_mount/sliding_windows/Num643.java
new file mode 100644
index 0000000..45b9fe9
--- /dev/null
+++ b/src/main/java/com/cool/ling_cha_mount/sliding_windows/Num643.java
@@ -0,0 +1,25 @@
+package com.cool.ling_cha_mount.sliding_windows;
+
+/**
+ * Created with IntelliJ IDEA.
+ *
+ * @Author: Cool
+ * @Date: 2024/10/03/17:14
+ * @Description:
+ */
+public class Num643 {
+
+    public double findMaxAverage(int[] nums, int k) {
+        int sum = 0;
+        for (int i = 0; i < k; i++) {
+            sum += nums[i];
+        }
+        int max = sum;
+        for (int i = k; i < nums.length; i++) {
+            sum += nums[i];
+            sum -= nums[i - k];
+            max = Math.max(max, sum);
+        }
+        return 1.0 * max / k;
+    }
+}