82. 删除排序链表中的重复元素 II

/**
 * @Description 一道中等题，还是要注意设置虚拟头结点，然后考虑循环不变量
 * @Date 2022/1/19 10:33 下午
 * @Author wuqichuan@zuoyebang.com
 **/
public class Solution {
    public ListNode deleteDuplicates(ListNode head) {
        ListNode dummyHead = new ListNode();
        dummyHead.next = head;
        ListNode cur = dummyHead;
        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 dummyHead.next;
    }
}