class Solution {
    public ListNode deleteDuplicates(ListNode head) {
        if(head==null)return head;
        ListNode temp = head;
        while(temp!=null&&temp.next!=null){//注意点
            if(temp.next.val==temp.val){
                ListNode node = temp ;
                while(node!=null&&node.next!=null&&node.next.val==node.val){
                    node = node.next;
                }
                temp.next = node.next;
            }
            temp = temp.next;
        }
        return head;
    }
}

自己的两种解法

class Solution {
public ListNode deleteDuplicates(ListNode head) {
        if (head == null)
            return null;
        ListNode ls = head;
        while (ls.next != null) {
            if (ls.val != ls.next.val) {
                ls = ls.next;
            } else {
                ls.next = ls.next.next;
            }
        }
        return head;
    }
}