diff --git a/src/main/java/com/cool/ling_cha_mount/sliding_windows/Num2461.java b/src/main/java/com/cool/ling_cha_mount/sliding_windows/Num2461.java
new file mode 100644
index 0000000..83e9c3a
--- /dev/null
+++ b/src/main/java/com/cool/ling_cha_mount/sliding_windows/Num2461.java
@@ -0,0 +1,55 @@
+package com.cool.ling_cha_mount.sliding_windows;
+
+import java.util.HashMap;
+import java.util.Map;
+
+/**
+ * Created with IntelliJ IDEA.
+ *
+ * @Author: Cool
+ * @Date: 2024/10/10/17:11
+ * @Description: 2461. 长度为 K 子数组中的最大和
+ * Hard 2
+ * Level 4
+ * Score 1553
+ */
+public class Num2461 {
+
+
+    /**
+     * 1
+     *
+     * @Author Cool
+     * @Date 17:11 2024/10/10
+     **/
+    public long maximumSubarraySum(int[] nums, int k) {
+        Map<Integer, Integer> map = new HashMap<>();
+        long sum = 0;
+        for (int i = 0; i < k; i++) {
+            map.put(nums[i], map.getOrDefault(nums[i], 0) + 1);
+            sum += nums[i];
+        }
+        long res = 0;
+        if (map.size() == k) {
+            res = sum;
+        }
+        for (int i = k; i < nums.length; i++) {
+            Integer left = map.get(nums[i - k]);
+            if (left==1) {
+                map.remove(nums[i - k]);
+            } else {
+                map.put(nums[i - k], left - 1);
+            }
+            map.put(nums[i], map.getOrDefault(nums[i], 0) + 1);
+            sum -= nums[i - k];
+            sum += nums[i];
+            if (map.size() == k) {
+                res = Math.max(sum, res);
+            }
+        }
+        return res;
+    }
+
+
+
+}