输入一个链表，反转链表后，输出链表的所有元素。

/* public class ListNode {      int val;      ListNode next = null;        ListNode(int val) {          this.val = val;      } }*/ public class Solution {      public ListNode ReverseList(ListNode head) {          if (head== null )              return null ;          ListNode newHead =  null ;          ListNode pNode = head;          ListNode pPrev =  null ;          while (pNode!= null ){              ListNode pNext = pNode.next;              if (pNext== null )                  newHead = pNode;              pNode.next = pPrev;              pPrev = pNode;              pNode = pNext;          }          return newHead;      } }

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