[leetcode]Remove Duplicates from Sorted List II

Remove Duplicates from Sorted List II

Given a sorted linked list, delete all nodes that have duplicate numbers, leaving only distinct numbers from the original list.

For example,
Given 1->2->3->3->4->4->5, return 1->2->5.
Given 1->1->1->2->3, return 2->3.

算法思路：

跟[leetcode]Remove Duplicates from Sorted List差不许多，只是加一个前驱节点和标记变量，以便删除重复节点。

public class Solution {
    public ListNode deleteDuplicates(ListNode head) {
        if(head == null || head.next == null) return head;
        ListNode hhead = new ListNode(0);
        hhead.next = head;
        ListNode one = hhead;
        ListNode two = head;
        boolean tag = false;
        while(two != null){
            tag = false;
            while(two.next != null && two.next.val == two.val) {
                two = two.next;
                tag = true;
            }
            if(tag){
                two = two.next;
                one.next = two;
            }else{
                one = two; 
                two = two.next;
            }
        }
        return hhead.next;
    }
}