题解 | #删除有序链表中重复的元素-II#

import java.util.*;

/*
 * public class ListNode {
 *   int val;
 *   ListNode next = null;
 * }
 */

public class Solution {
    /**
     *
     * @param head ListNode类
     * @return ListNode类
     */
    public ListNode deleteDuplicates (ListNode head) {
        if (head == null) return null;
        ListNode cur = head;
        List<Integer> list = new ArrayList<>();
        while (cur != null) {
            if (cur.next != null && cur.val == cur.next.val) {
                cur.next = cur.next.next;
                if (!list.contains(cur.val))
                    list.add(cur.val);
                continue;
            }
            cur = cur.next;
        }
        if (list.size() == 0) {
            return head;
        }
        cur = head;
        ListNode prev = cur;
        while (cur != null) {
            if (list.contains(head.val)) {
                head = head.next;
                cur = head;
                prev = cur;
            } else if (list.contains(cur.val)) {
                prev.next = cur.next;
                cur = cur.next;
                continue;

            } else {
                prev = cur;
                cur = cur.next;
            }


        }
        return head;
    }
}