LeetCode 206

Reverse Linked List

Reverse a singly linked list.

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

 1 /*************************************************************************
 2     > File Name: LeetCode206.c
 3     > Author: Juntaran
 4     > Mail: JuntaranMail@gmail.com
 5     > Created Time: Wed 18 May 2016 21:15:51 PM CST
 6  ************************************************************************/
 7 
 8 /*************************************************************************
 9     
10     Reverse Linked List
11     
12     Reverse a singly linked list.
13 
14     Hint:
15     A linked list can be reversed either iteratively or recursively. 
16     Could you implement both?
17 
18  ************************************************************************/
19 
20 #include "stdio.h"
21 
22 /**
23  * Definition for singly-linked list.
24  * struct ListNode {
25  *     int val;
26  *     struct ListNode *next;
27  * };
28  */
29 struct ListNode* reverseList(struct ListNode* head) 
30 {
31     if( head==NULL || head->next==NULL )
32     {
33         return head;
34     }
35     struct ListNode* temp    = NULL;
36     struct ListNode* newhead = NULL;
37     
38     while( head != NULL )
39     {
40         temp = head->next;
41         head->next = newhead;
42         newhead = head;
43         head = temp;
44     }
45      
46     return newhead;
47 }