昨日未完成hard今日完成

src/main/java/com/cool/hot100/linkedlist/Num25.java

@@ -2,8 +2,6 @@ package com.cool.hot100.linkedlist;
 
 import org.junit.Test;
 
-import java.util.ArrayList;
-import java.util.List;
 
 /**
  * @Author Cool
@@ -13,41 +11,37 @@ import java.util.List;
  **/
 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) {
+            ListNode tail=pre;
             for (int i = 0; i < k; i++) {
-                head = head.next;
-                if (head == null) {
+                tail = tail.next;
+                if (tail == null) {
                     return hair.next;
                 }
             }
-            ListNode next=head.next;
-            ListNode[] reverse = reverse(head,next);
-            pre=nodeHead;
-            nodeHead.next = next;
-            node = next;
+            ListNode next=tail.next;
+            ListNode[] reverse = reverse(head,tail);
+            head=reverse[0];
+            tail=reverse[1];
+            pre.next=head;
+            tail.next=next;
+            head=next;
+            pre=tail;
 
         }
-        return newHead;
+        return hair.next;
 
     }
 
     private ListNode[] reverse(ListNode head,ListNode next) {
         ListNode node = head;
         ListNode pre = null;
-        while (node != null) {
+        ListNode nxt=next.next;
+        while (node != nxt) {
             ListNode net = node.next;
             node.next = pre;
             pre = node;