剑指 Offer 24. 反转链表

题目链接：https://leetcode.cn/problems/fan-zhuan-lian-biao-lcof/description/?favorite=xb9nqhhg

题目：

代码：

/**
 * 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  *ans;
        ans=NULL;
        while(head!=NULL)
        {
          ListNode  *tmp=head->next;
           head->next=ans;
           ans=head;
           head=tmp;
        }
        return ans;

    }
};