diff --git a/budd-common/src/main/java/io/github/ehlxr/MyBloomFilter.java b/budd-common/src/main/java/io/github/ehlxr/MyBloomFilter.java
new file mode 100644
index 0000000..47031e4
--- /dev/null
+++ b/budd-common/src/main/java/io/github/ehlxr/MyBloomFilter.java
@@ -0,0 +1,127 @@
+/*
+ * The MIT License (MIT)
+ *
+ * Copyright © 2021 xrv <xrg@live.com>
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+package io.github.ehlxr;
+
+import java.util.BitSet;
+
+/**
+ * @author ehlxr
+ * @since 2021-12-16 09:36.
+ */
+public class MyBloomFilter {
+    /**
+     * 一个长度为10 亿的比特位
+     */
+    private static final int DEFAULT_SIZE = 256 << 22;
+
+    /**
+     * 为了降低错误率，使用加法hash算法，所以定义一个8个元素的质数数组
+     */
+    private static final int[] SEEDS = {3, 5, 7, 11, 13, 31, 37, 61};
+
+    /**
+     * 相当于构建 8 个不同的hash算法
+     */
+    private static final HashFunction[] HASH_FUNCS = new HashFunction[SEEDS.length];
+
+    /**
+     * 初始化布隆过滤器的 bitmap
+     */
+    private static final BitSet BIT_SET = new BitSet(DEFAULT_SIZE);
+
+    /**
+     * 添加数据
+     *
+     * @param value 需要加入的值
+     */
+    public static void add(String value) {
+        if (value != null) {
+            for (HashFunction f : HASH_FUNCS) {
+                //计算 hash 值并修改 bitmap 中相应位置为 true
+                BIT_SET.set(f.hash(value), true);
+            }
+        }
+    }
+
+    /**
+     * 判断相应元素是否存在
+     *
+     * @param value 需要判断的元素
+     * @return 结果
+     */
+    public static boolean contains(String value) {
+        if (value == null) {
+            return false;
+        }
+        boolean ret = true;
+        for (HashFunction f : HASH_FUNCS) {
+            ret = BIT_SET.get(f.hash(value));
+            //一个 hash 函数返回 false 则跳出循环
+            if (!ret) {
+                break;
+            }
+        }
+        return ret;
+    }
+
+    /**
+     * 模拟用户是不是会员，或用户在不在线。。。
+     */
+    public static void main(String[] args) {
+        for (int i = 0; i < SEEDS.length; i++) {
+            HASH_FUNCS[i] = new HashFunction(DEFAULT_SIZE, SEEDS[i]);
+        }
+
+        // 添加1亿数据
+        for (int i = 0; i < 1_0000_0000; i++) {
+            add(String.valueOf(i));
+        }
+        String id = "123456789";
+        add(id);
+
+        System.out.println(contains(id));   // true
+        System.out.println("" + contains("234567890"));  //false
+    }
+}
+
+class HashFunction {
+    private final int size;
+    private final int seed;
+
+    public HashFunction(int size, int seed) {
+        this.size = size;
+        this.seed = seed;
+    }
+
+    public int hash(String value) {
+        int result = 0;
+        int len = value.length();
+        for (int i = 0; i < len; i++) {
+            result = seed * result + value.charAt(i);
+        }
+        int r = (size - 1) & result;
+        return (size - 1) & result;
+    }
+}
\ No newline at end of file
diff --git a/budd-common/src/main/java/io/github/ehlxr/datastructure/linkedlist/ListNode.java b/budd-common/src/main/java/io/github/ehlxr/datastructure/linkedlist/ListNode.java
new file mode 100644
index 0000000..e8bf51e
--- /dev/null
+++ b/budd-common/src/main/java/io/github/ehlxr/datastructure/linkedlist/ListNode.java
@@ -0,0 +1,64 @@
+/*
+ * The MIT License (MIT)
+ *
+ * Copyright © 2021 xrv <xrg@live.com>
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+package io.github.ehlxr.datastructure.linkedlist;
+
+/**
+ * 链表节点数据结构
+ *
+ * @author ehlxr
+ * @since 2021-12-23 14:41.
+ */
+public class ListNode {
+    private int val;
+    private ListNode next;
+
+    public ListNode(int val, ListNode next) {
+        this.val = val;
+        this.next = next;
+    }
+
+    public int getVal() {
+        return val;
+    }
+
+    public void setVal(int val) {
+        this.val = val;
+    }
+
+    public ListNode getNext() {
+        return next;
+    }
+
+    public void setNext(ListNode next) {
+        this.next = next;
+    }
+
+    @Override
+    public String toString() {
+        return "SingleNode{" +
+                "val=" + val +
+                '}';
+    }
+}
diff --git a/budd-common/src/main/java/io/github/ehlxr/datastructure/linkedlist/ReverseLinkedList.java b/budd-common/src/main/java/io/github/ehlxr/datastructure/linkedlist/ReverseLinkedList.java
new file mode 100644
index 0000000..df0cee0
--- /dev/null
+++ b/budd-common/src/main/java/io/github/ehlxr/datastructure/linkedlist/ReverseLinkedList.java
@@ -0,0 +1,110 @@
+/*
+ * The MIT License (MIT)
+ *
+ * Copyright © 2021 xrv <xrg@live.com>
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+package io.github.ehlxr.datastructure.linkedlist;
+
+/**
+ * @author ehlxr
+ * @since 2021-12-23 14:40.
+ */
+public class ReverseLinkedList {
+    public static void main(String[] args) {
+        ListNode n5 = new ListNode(5, null);
+        ListNode n4 = new ListNode(4, n5);
+        ListNode n3 = new ListNode(3, n4);
+        ListNode n2 = new ListNode(2, n3);
+        ListNode n1 = new ListNode(1, n2);
+        ListNode head = new ListNode(0, n1);
+
+        print(head);
+
+        System.out.println("-------------");
+        // head = reverse(head);
+        head = reverse2(head);
+        // head = reverse3(head, null);
+        print(head);
+
+    }
+
+    public static void print(ListNode head) {
+        if (head == null) {
+            return;
+        }
+
+        ListNode n = head;
+        while (n != null) {
+            System.out.println(n);
+            n = n.getNext();
+        }
+    }
+
+    // 循环方式
+    public static ListNode reverse(ListNode head) {
+        if (head == null || head.getNext() == null) {
+            return head;
+        }
+        ListNode pre = null;
+
+        ListNode cur = head;
+        while (cur != null) {
+            ListNode next = cur.getNext();
+            cur.setNext(pre);
+            pre = cur;
+
+            cur = next;
+        }
+
+        return pre;
+    }
+
+    // 递归一
+    public static ListNode reverse2(ListNode head) {
+        if (head == null || head.getNext() == null) {
+            return head;
+        }
+
+        ListNode next = head.getNext();
+        ListNode node = reverse2(next);
+
+        head.getNext().setNext(head);
+        head.setNext(null);
+
+        return node;
+    }
+
+    // 递归二
+    public static ListNode reverse3(ListNode head, ListNode pre) {
+        if (head == null) {
+            return pre;
+        }
+
+        ListNode next = head.getNext();
+        ListNode node = reverse3(next, head);
+
+        head.setNext(pre);
+
+        return node;
+    }
+
+}