Reverse Linked List

 1 /**
 2  * Definition for ListNode.
 3  * public class ListNode {
 4  *     int val;
 5  *     ListNode next;
 6  *     ListNode(int val) {
 7  *         this.val = val;
 8  *         this.next = null;
 9  *     }
10  * }
11  */ 
12 public class Solution {
13     /**
14      * @param head: The head of linked list.
15      * @return: The new head of reversed linked list.
16      */
17     public ListNode reverse(ListNode head) {
18         if (head == null) return head;
19         ListNode prev = null;
20         ListNode cur = head;
21         ListNode next = null;
22         while (cur != null) {
23             next = cur.next;
24             cur.next = prev;
25             prev = cur;
26             cur = next;
27         }
28         return prev;
29     }
30 }