Leetcode solution 01：206 Reverse Linked List

Reverse Linked List

Reverse a singly linked list.

/**
* 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) {
}
};

题目就是简单的把一个链表倒转过来

刚开始想的时候忘记了以前可以直接在遍历链表的过程中同时建立起一个方向链表，

所以还弄了个中间储存的步骤，结果没通过OJ

后来想想可以直接一遍完成，附上代码

/**
* 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 *pre = nullptr, *next = nullptr;
while (head)
{
next = head->next;
head->next = pre;
pre = head;
head = next;
}
return pre;
}
};