题目：翻转链表

翻转一个链表

您在真实的面试中是否遇到过这个题？

Yes

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样例

给出一个链表1->2->3->null，这个翻转后的链表为3->2->1->null

挑战

在原地一次翻转完成

标签 Expand

链表

相关题目 Expand

**
* Definition for ListNode.
* public class ListNode {
*     int val;
*     ListNode next;
*     ListNode(int val) {
*         this.val = val;
*         this.next = null;
*     }
* }
*/
public class Solution {
    /**
     * @param head: The head of linked list.
     * @return: The new head of reversed linked list.
     */
    public ListNode reverse(ListNode head) {
        // write your code here
        if(null==head||head.next==null) return head;
         ListNode pre = head;
         ListNode next  =  head.next;
         ListNode nextnext = next.next;
         pre.next = null;
         while(next!=null){
              nextnext = next.next;
              next.next = pre;
              pre = next;
              next  = nextnext;
         }
         return pre;
    }
}