206. Reverse Linked List

/**
 * Definition for singly-linked list.
 * public class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode() {}
 *     ListNode(int val) { this.val = val; }
 *     ListNode(int val, ListNode next) { this.val = val; this.next = next; }
 * }
 */
class Solution 
{
    public ListNode reverseList(ListNode head) 
    {
        if(head==null || head.next==null)
            return head;
        ListNode cur1=head;
        ListNode cur2;
        ListNode prev=null;
        while(cur1!=null)
        {
            cur2=cur1;
            cur1=cur1.next;
            cur2.next=prev;
            prev=cur2;
        }
        head=prev;
        return head;
    }
}