diff --git a/src/main/java/com/cool/hot100/linkedlist/Num25.java b/src/main/java/com/cool/hot100/linkedlist/Num25.java
new file mode 100644
index 0000000..78dd779
--- /dev/null
+++ b/src/main/java/com/cool/hot100/linkedlist/Num25.java
@@ -0,0 +1,70 @@
+package com.cool.hot100.linkedlist;
+
+import org.junit.Test;
+
+import java.util.ArrayList;
+import java.util.List;
+
+/**
+ * @Author Cool
+ * @Date 23:30 2024/8/23
+ * DayNumber 2
+ * Hard 3
+ **/
+public class Num25 {
+
+    /**
+     * Date 2024/8/23
+     * DayNumber 2
+     * Hard 3
+     *
+     * @param head
+     * @param k
+     * @return
+     */
+    public ListNode reverseKGroup(ListNode head, int k) {
+        ListNode hair=new ListNode(0);
+        hair.next=head;
+        ListNode pre = hair;
+        while (head != null) {
+            for (int i = 0; i < k; i++) {
+                head = head.next;
+                if (head == null) {
+                    return hair.next;
+                }
+            }
+            ListNode next=head.next;
+            ListNode[] reverse = reverse(head,next);
+            pre=nodeHead;
+            nodeHead.next = next;
+            node = next;
+
+        }
+        return newHead;
+
+    }
+
+    private ListNode[] reverse(ListNode head,ListNode next) {
+        ListNode node = head;
+        ListNode pre = null;
+        while (node != null) {
+            ListNode net = node.next;
+            node.next = pre;
+            pre = node;
+            node = net;
+        }
+        return new ListNode[]{next,head};
+    }
+
+    @Test
+    public void test() {
+        ListNode node1 = new ListNode(7);
+        ListNode node2 = new ListNode(6, node1);
+        ListNode node3 = new ListNode(5, node2);
+        ListNode node4 = new ListNode(4, node3);
+        ListNode node5 = new ListNode(3, node4);
+        ListNode node6 = new ListNode(2, node5);
+        ListNode node7 = new ListNode(1, node6);
+        reverseKGroup(node7, 2);
+    }
+}