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;
* next = null;
* }
* }
*/
public class Solution {
public ListNode deleteDuplicates(ListNode head) { if(head==null) return head;
if(head.next==null) return head; ListNode pre=head;//save the pre to delete
ListNode cur=head.next;
while(cur!=null)
{
if(cur.val==pre.val)
{ pre.next=cur.next;//删除cur节点
cur=cur.next; //处理下一个节点 }
else
{
pre=pre.next;
cur=cur.next; } } return head; }
}