图解剑指 Offer II 024. 反转链表（LeetCode）

class Solution {
public:
    ListNode* reverseList(ListNode* head) {
        ListNode *new_head = NULL;
        while(head)    
        {
            ListNode *next = head->next;     //备份head->next;
            head->next = new_head;           //将head->next的指向修改
            new_head = head;                 //移动new_head的位置
            head = next;                     //head 等于其备份的地方
        }
        return new_head;
    }
};