翻转链表

反转一个单链表。

示例:

输入: 1->2->3->4->5->NULL
输出: 5->4->3->2->1->NULL

/**
 * Definition for singly-linked list.
 * struct ListNode {
 *     int val;
 *     ListNode *next;
 *     ListNode(int x) : val(x), next(NULL) {}
 * };
 */
class Solution {
public:
    ListNode* reverseList(ListNode* head) {
        ListNode* Pre=NULL, *Cur=head;
        while(Cur){
            ListNode* Next = Cur->next;
            Cur->next = Pre;
            Pre = Cur;
            Cur = Next;
        }
        return Pre;
    }
};