Given a sorted linked list, delete all duplicates such that each element appear only once.
Example 1:
Input: ->->
Output: ->Example 2:
Input: ->->->->
Output: ->->
问题描述：给定一个已排序链表，移除重复元素
代码：
public ListNode DeleteDuplicates(ListNode head) {
ListNode l = head;
while(l != null && l.next != null){
if(l.val == l.next.val){
l.next = l.next.next;
}else{
l = l.next;
}
}
return head;
}
