#Leetcode# 206. Reverse Linked List

https://leetcode.com/problems/reverse-linked-list/

 

Reverse a singly linked list.

Example:

Input: 1->2->3->4->5->NULL
Output: 5->4->3->2->1->NULL

Follow up:

A linked list can be reversed either iteratively or recursively. Could you implement both?

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 *revhead = NULL;
        ListNode *pnode = head;
        ListNode *pre = NULL;
        
        while(pnode) {
            if(!pnode -> next)
                revhead = pnode;
            
            ListNode *nxt = pnode -> next;
            pnode -> next = pre;
            pre = pnode;
            pnode = nxt;
        }
        return revhead;
    }
};

　　反转链表 一会粗去转一圈吹吹风 有 1.. 心情不好 很迷茫啊

FHFHFH