Leetcode No.206 反转链表

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;
        ListNode *current=head;
        while(current!=NULL){
            ListNode *nextNode=current->next;
            current->next=pre;
            pre=current;
            current=nextNode;
        }
        return pre;
    }
};