给定一个已排序的链表的头 head ， 删除原始链表中所有重复数字的节点，只留下不同的数字 。返回 已排序的链表 。

示例 1：

输入：head = [1,2,3,3,4,4,5]
输出：[1,2,5]

示例 2：

输入：head = [1,1,1,2,3]
输出：[2,3]

提示：

• 链表中节点数目在范围 [0, 300] 内
• -100 <= Node.val <= 100
• 题目数据保证链表已经按升序 排列

题解:

code：

/*** 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 deleteDuplicates(ListNode head) {if (head == null) {return head;}ListNode dumy = new ListNode(0, head);ListNode cur = dumy;while (cur.next != null && cur.next.next != null) {if (cur.next.val == cur.next.next.val) {int x = cur.next.val;while (cur.next != null && cur.next.val == x) {cur.next = cur.next.next;}} else {cur = cur.next;}}return dumy.next;}
}