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 ListNode(int val) {
 *     this.val = val;
 *   }
 * }
 */

public class Solution {
    /**
     * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
     *
     *
     * @param head ListNode类
     * @return ListNode类
     */
    public ListNode deleteDuplicates (ListNode head) {
        // write code here
        if (head == null) {
            return null;
        }
        if (head.next == null) {
            return head;
        }
        ListNode nHead = new ListNode(-1);
        nHead.next = head;
        ListNode cur = nHead;
        while (cur.next != null && cur.next.next != null) {
            if (cur.next.val == cur.next.next.val) {
                int tmp = cur.next.val;
                while (cur.next != null && tmp == cur.next.val) {
                    cur.next = cur.next.next;
                }
            } else {
                cur = cur.next;
            }
        }
        return nHead.next;
        //为什么设置头节点,因为第一个节点可能被删除
    }
}