https://oj.leetcode.com/problems/remove-duplicates-from-sorted-list-ii/

Remove Duplicates from Sorted List II.java

/**
 * Definition for singly-linked list.
 * public class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode(int x) {
 *         val = x;
 *         next = null;
 *     }
 * }
 */
public class Solution {
    public ListNode deleteDuplicates(ListNode head) {
        ListNode ret = null;
        ListNode p = head;
        ListNode ret_tail = null;
        boolean flag = true;
        while (p != null){
            if ((p.next == null) || ((p.next != null) && (p.next.val != p.val))){
                if (flag){
                    ListNode q = new ListNode(p.val);
                    if (ret == null){
                        ret = q;
                        ret_tail = ret;
                    }else{
                        ret_tail.next = q;
                        ret_tail = ret_tail.next;
                    }
                }else{
                    flag = true;
                }
            }else{
                flag = false;
            }
            p = p.next;
        }
        return ret;
    }
}