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
     */
    // 重复的全给删了,一个不留!
    public ListNode deleteDuplicates (ListNode head) {
        if(head == null || head.next == null) return head;
        ListNode fake_head = new ListNode(-1);
        fake_head.next = head;
        ListNode pre = fake_head,cur = head,next = head.next;
        
        while(next != null){
            if(cur.val == next.val){
                while(cur != null && next != null && cur.val == next.val){
                    cur = next;
                    next = next.next;
                } // 跳过重复元素!
                pre.next = next;
            }else {
                 pre = pre.next;
            }
          
           if(next != null) {
                cur = next;
                next = next.next;
           }
        }
        return fake_head.next;
    }
}