Reverse a singly linked list.

思路还是很简单的,有三个节点的临时变量就可以了,主要是代码要写得精炼。

代码如下:

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