[Lintcode]Reverse Linked List

Example

For linked list 1->2->3, the reversed linked list is 3->2->1

Challenge

Reverse it in-place and in one-pass

值可以改动的话，用双指针，链表保持不变，更新值即可。值不可以改变的话，需要改变链表指针

public class Solution {    /**     * @param head: The head of linked list.     * @return: The new head of reversed linked list.     */    public ListNode reverse(ListNode head) {        ListNode prev = null;                while(head != null) {            ListNode tmp = head.next;            head.next = prev;            prev = head;            head = tmp;        }        return prev;    }}