剑指24: 反转链表

 1 /**
 2  * Definition for singly-linked list.
 3  * struct ListNode {
 4  *     int val;
 5  *     ListNode *next;
 6  *     ListNode(int x) : val(x), next(NULL) {}
 7  * };
 8  */
 9 class Solution {
10 public:
11     ListNode* reverseList(ListNode* head) {
12         if(head==nullptr || head->next==nullptr)
13             return head;
14         ListNode *curptr, *nextptr, *nextnextptr;
15         curptr=head;
16         nextptr=head->next;
17         nextnextptr=nextptr->next;
18         head->next=nullptr;
19         while(nextnextptr!=nullptr){
20             nextptr->next=curptr;
21             curptr=nextptr;
22             nextptr=nextnextptr;
23             nextnextptr=nextnextptr->next;
24         }
25         nextptr->next=curptr;
26         return nextptr;
27     }
28 };