【LeetCode】206. Reverse Linked List

题目：

提示：

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) {
if(!head) return NULL;
ListNode *pre = head, *cur = head->next;
pre->next = NULL;
ListNode *tmp;
while (cur) {
tmp = cur->next;
cur->next = pre;
pre = cur;
cur = tmp;
}
return pre;
}
};

/**
* 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) {
return reverseNode(head, NULL);
}

ListNode* reverseNode(ListNode* head, ListNode* newHead) {
if (!head) return newHead;
ListNode *next = head->next;
head->next = newHead;
return reverseNode(next, head);
}
};