LeetCode怎么删除排序链表中的重复元素

示例 1:
输入: 1->1->2输出: 1->2示例 2:
输入: 1->1->2->3->3输出: 1->2->3

public class DeleteDuplicatesTest {    public static void main(String[] args) {        ListNode l1 = new ListNode(1);        ListNode l2 = new ListNode(1);        ListNode l3 = new ListNode(2);        l1.next = l2;        l2.next = l3;        ListNode listNode = deleteDuplicates(l1);        System.out.println("listNode = " + listNode);
    }
    public static ListNode deleteDuplicates(ListNode head) {        if (head == null) {            return null;        }        if (head.next == null) {            return head;        }        ListNode tempNode = head;        while (tempNode.next != null) {            if (tempNode.val == tempNode.next.val) {                tempNode.next = tempNode.next.next;            } else {                tempNode = tempNode.next;            }        }        return head;    }}