题解 | #删除有序链表中重复的元素-II#

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

public class Solution {
    /**
     * 
     * @param head ListNode类 
     * @return ListNode类
     */
    public ListNode deleteDuplicates (ListNode head) {
        // write code here
        if(head == null || head.next == null){
            return head;
        }
        ListNode newHead = new ListNode(-1);
        newHead.next = head;
        ListNode currentNode = head;
        ListNode pre = newHead;
        int count = 0;
        while(currentNode != null && currentNode.next != null){
               if(currentNode.val == currentNode.next.val){
                   count ++;
                   currentNode.next = currentNode.next.next;
               }else{
                   if(count >0){
                       pre.next = currentNode.next;
                       count = 0;
                   }else{
                       pre = currentNode;
                   }
                   currentNode = currentNode.next;
               }
             
            
        }
        if(count > 0){
            pre.next = currentNode.next;
        }
        return newHead.next;
    }
}