diff --git a/5.leetcode/src/com/fanxb/common/Q138.java b/5.leetcode/src/com/fanxb/common/Q138.java
index 947f82c..9566de4 100644
--- a/5.leetcode/src/com/fanxb/common/Q138.java
+++ b/5.leetcode/src/com/fanxb/common/Q138.java
@@ -43,4 +43,21 @@ public class Q138 {
         }
         return res.next;
     }
+
+    public Node newCopy(Node head) {
+        Map<Node, Node> map = new HashMap<>();
+        Node cur = head;
+        while (cur != null) {
+            map.put(cur, new Node(cur.val));
+            cur = cur.next;
+        }
+        cur = head;
+        while (cur != null) {
+            Node n = map.get(cur);
+            n.random = map.get(cur.random);
+            n.next = map.get(cur.next);
+            cur = cur.next;
+        }
+        return map.get(head);
+    }
 }
diff --git a/5.leetcode/src/com/fanxb/common/Q141.java b/5.leetcode/src/com/fanxb/common/Q141.java
new file mode 100644
index 0000000..bb7b36d
--- /dev/null
+++ b/5.leetcode/src/com/fanxb/common/Q141.java
@@ -0,0 +1,33 @@
+package com.fanxb.common;
+
+import java.util.HashMap;
+import java.util.Map;
+
+/**
+ * TODO
+ *
+ * @author FleyX
+ * @date 2022/3/3 22:35
+ */
+public class Q141 {
+    private static class Node {
+        int val;
+        Node next;
+
+        public Node(int val) {
+            this.val = val;
+            this.next = null;
+        }
+    }
+
+    public boolean hasCycle(ListNode head) {
+        if (head == null || head.next == null) return false;
+        ListNode fast = head, slow = head;
+        while (fast.next != null && fast.next.next != null) {
+            fast = fast.next.next;
+            slow = slow.next;
+            if (fast == slow) return true;
+        }
+        return false;
+    }
+}
diff --git a/5.leetcode/src/com/fanxb/common/Q2.java b/5.leetcode/src/com/fanxb/common/Q2.java
index f865af8..11c63dd 100644
--- a/5.leetcode/src/com/fanxb/common/Q2.java
+++ b/5.leetcode/src/com/fanxb/common/Q2.java
@@ -62,17 +62,39 @@ public class Q2 {
         return res;
     }
 
+    public ListNode addTwoNumbers1(ListNode l1, ListNode l2) {
+        ListNode res = new ListNode(0);
+        ListNode temp = null;
+        //是否进位
+        boolean jw = false;
+        while (l1 != null || l2 != null) {
+            if (temp == null) temp = res;
+            else {
+                temp.next = new ListNode(0);
+                temp = temp.next;
+            }
+            if (l1 != null) {
+                temp.val += l1.val;
+                l1 = l1.next;
+            }
+            if (l2 != null) {
+                temp.val += l2.val;
+                l2 = l2.next;
+            }
+            if (jw) {
+                temp.val += 1;
+                jw = false;
+            }
+            if (temp.val >= 10) {
+                jw = true;
+                temp.val -= 10;
+            }
+        }
+        if (jw) temp.next = new ListNode(1);
+        return res;
+    }
+
+
     public static void main(String[] args) {
-        ListNode l1 = new ListNode(2);
-        l1.next = new ListNode(4);
-        l1.next.next = new ListNode(9);
-
-        ListNode l2 = new ListNode(5);
-        l2.next = new ListNode(6);
-        l2.next.next = new ListNode(4);
-        l2.next.next.next = new ListNode(9);
-
-        new Q2().addTwoNumbers(l1, l2);
-//        new Q2().addTwoNumbers(new ListNode(0), new ListNode(0));
     }
 }
diff --git a/5.leetcode/src/com/fanxb/common/Q21.java b/5.leetcode/src/com/fanxb/common/Q21.java
new file mode 100644
index 0000000..caf228b
--- /dev/null
+++ b/5.leetcode/src/com/fanxb/common/Q21.java
@@ -0,0 +1,30 @@
+package com.fanxb.common;
+
+public class Q21 {
+    public ListNode mergeTwoLists(ListNode list1, ListNode list2) {
+        if (list2 == null) return list1;
+        if (list1 == null) return list2;
+        ListNode res = null;
+        if (list1.val < list2.val) {
+            res = list1;
+            list1 = list1.next;
+        } else {
+            res = list2;
+            list2 = list2.next;
+        }
+        ListNode temp = res;
+        while (list1 != null && list2 != null) {
+            if (list1.val < list2.val) {
+                temp.next = list1;
+                list1 = list1.next;
+            } else {
+                temp.next = list2;
+                list2 = list2.next;
+            }
+            temp = temp.next;
+        }
+        if (list1 != null) temp.next = list1;
+        else temp.next = list2;
+        return res;
+    }
+}
diff --git a/5.leetcode/src/com/fanxb/common/Q92.java b/5.leetcode/src/com/fanxb/common/Q92.java
new file mode 100644
index 0000000..79b6dc6
--- /dev/null
+++ b/5.leetcode/src/com/fanxb/common/Q92.java
@@ -0,0 +1,67 @@
+package com.fanxb.common;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+import java.util.Stack;
+
+/**
+ * Created with IntelliJ IDEA
+ *
+ * @author fanxb
+ * Date: 2020/6/9 15:10
+ */
+public class Q92 {
+
+    public class ListNode {
+        int val;
+        ListNode next;
+
+        ListNode() {
+        }
+
+        ListNode(int val) {
+            this.val = val;
+        }
+
+        ListNode(int val, ListNode next) {
+            this.val = val;
+            this.next = next;
+        }
+    }
+
+    public ListNode reverseBetween(ListNode head, int left, int right) {
+        if (left == right) {
+            return head;
+        }
+        //node1 left位置前一个节点，node2 right位置后一个指针
+        ListNode node1 = null, leftNode = null, node2 = null, rightNode = null;
+        ListNode last = null, temp = head, next = null;
+        int count = 0;
+        while (temp != null) {
+            count++;
+            next = temp.next;
+            if (left == count) {
+                node1 = last;
+                leftNode = temp;
+            }
+            if (right == count) {
+                node2 = next;
+                rightNode = temp;
+            }
+            if (count > left && count <= right) {
+                temp.next = last;
+            }
+
+            last = temp;
+            temp = next;
+        }
+        leftNode.next = node2;
+        if (node1 != null) {
+            node1.next = rightNode;
+        } else {
+            head = rightNode;
+        }
+        return head;
+    }
+}