反转链表

Description：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 || head.next == null) return head;        ListNode cur = head;        ListNode pre = null;        ListNode reverseHead = null;        while (cur != null) {            ListNode curNext = cur.next;            cur.next = pre;            if (curNext == null)                reverseHead = cur;            pre = cur;            cur = curNext;        }        return reverseHead;    }}