Given a sorted linked list, delete all duplicates such that each element appear only once.

For example,Given 1->1->2, return 1->2. Given 1->1->2->3->3, return 1->2->3.

Solution:

/**
 * Definition for singly-linked list.
 * public class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode(int x) { val = x; }
 * }
 */
public class Solution 
{
    public ListNode deleteDuplicates(ListNode head) 
    {
        if(head == null) return null;
        
        ListNode left = head;
        ListNode right = head.next;
        
        while(right != null)
        {
            if(right.val == left.val)
            {
                right = right.next;
                left.next = right;
            }
            else
            {
                left = right;
                right = right.next;
            }
        }
        return head;
    }
}