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) {
        if(head == null || head.next == null) return head;
        ListNode dummy = new ListNode(0);
        dummy.next = head;
        ListNode pre = dummy;
        ListNode cur = head;
        while(cur != null && cur.next != null){
            if(cur.next.val == cur.val){
                cur = cur.next;
                while(cur.next != null && cur.next.val == cur.val) cur = cur.next;
                pre.next = cur.next;
                cur = cur.next;
                continue;
            }
            pre = cur;
            cur = cur.next;
        }
        return dummy.next;
    }
}