diff --git a/pom.xml b/pom.xml
index 555273c..50302a9 100644
--- a/pom.xml
+++ b/pom.xml
@@ -13,5 +13,12 @@
         <maven.compiler.target>17</maven.compiler.target>
         <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
     </properties>
+    <dependencies>
+        <dependency>
+            <groupId>org.apache.commons</groupId>
+            <artifactId>commons-collections4</artifactId>
+            <version>4.4</version>
+        </dependency>
+    </dependencies>
 
 </project>
\ No newline at end of file
diff --git a/src/main/java/com/dota/Solution.java b/src/main/java/com/dota/Solution.java
index e13d70e..6be93ea 100644
--- a/src/main/java/com/dota/Solution.java
+++ b/src/main/java/com/dota/Solution.java
@@ -1,8 +1,18 @@
 package com.dota;
 
+import org.apache.commons.collections4.list.TreeList;
+
 import java.util.HashMap;
 
 public class Solution {
+	public static void main(String[] args) {
+		var a = new TreeList<Integer>();
+		a.add(1);
+		a.add(2);
+		a.add(1);
+		System.out.println(a.get(2));
+		Integer.bitCount(1231);
+	}
 	// 1423. 可获得的最大点数
 	public int maxScore(int[] cardPoints, int k) {
 		int max;
diff --git a/src/main/java/com/dota/slidingWindow/_2653/Solution.java b/src/main/java/com/dota/slidingWindow/_2653/Solution.java
new file mode 100644
index 0000000..380be31
--- /dev/null
+++ b/src/main/java/com/dota/slidingWindow/_2653/Solution.java
@@ -0,0 +1,30 @@
+package com.dota.slidingWindow._2653;
+
+class Solution {
+	public int[] getSubarrayBeauty(int[] nums, int k, int x) {
+		int n = nums.length;
+		int[] res = new int[n - k + 1];
+		int[] dp = new int[101];
+		for (int i = 0; i < k - 1; i++) {
+			dp[nums[i] + 50]++;
+		}
+
+		for (int i = k - 1; i < n; i++) {
+			dp[nums[i] + 50]++;
+			int left = x;
+			for (int j = 0; j < 101; j++) {
+				left -= dp[j];
+				if (left <= 0) {
+					res[i - k + 1] = j - 50;
+					if (res[i-k+1] > 0) {
+						res[i-k+1] = 0;
+					}
+					break;
+				}
+			}
+			dp[nums[i - k + 1] + 50]--;
+		}
+
+		return res;
+	}
+}
\ No newline at end of file
diff --git a/src/main/java/com/dota/str/_2109/Solution.java b/src/main/java/com/dota/str/_2109/Solution.java
new file mode 100644
index 0000000..3b8bc08
--- /dev/null
+++ b/src/main/java/com/dota/str/_2109/Solution.java
@@ -0,0 +1,18 @@
+package com.dota.str._2109;
+
+class Solution {
+	public String addSpaces(String s, int[] spaces) {
+		var sb = new StringBuilder();
+		int idx = 0;
+		int i = 0;
+		for (char c : s.toCharArray()) {
+			if (idx<spaces.length && i == spaces[idx]) {
+				sb.append(' ');
+				idx++;
+			}
+			sb.append(c);
+			i++;
+		}
+		return sb.toString();
+	}
+}
\ No newline at end of file