206 Reverse Linked List

链接：https://leetcode.com/problemset/algorithms/
问题描述：
Reverse a singly linked list.

click to show more hints.

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

这个问题是链表求逆，废话不多，直接上代码吧。
递归版：

struct ListNode* reverseList(struct ListNode* head){    if(head==NULL||head->next==NULL) return head;    struct ListNode *temp1=head;    struct ListNode *temp2;    while(temp1->next!=NULL)    {        temp2=temp1;        temp1=temp1->next;    }     temp2->next=NULL;    temp1->next=temp2;    reverseList(head);    return temp1;}

非递归版：

struct ListNode* reverseList(struct ListNode* head){    if(head==NULL||head->next==NULL) return head;    struct ListNode *temp1=NULL;    struct ListNode *temp2=NULL;    while(head!=NULL)    {      temp2=head->next;      head->next=temp1;      temp1=head;      head=temp2;    }     return temp1;}