Remove Duplicates from Sorted List

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.

 

/**
 * 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 head;
    	}
    	ListNode start = head;
    	ListNode end = head.next;
    	while (end != null) {
    		if (start.val == end.val) {
    			end = end.next;
    			if (end == null) {
    				start.next = null;
    			}
    		} else {
    			start.next = end;
    			start = start.next;
    			end = end.next;
    		}
    	}
    	return head;
    }
}