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 dummyHead = new ListNode(-1);
        dummyHead.next = head;
        ListNode curr = dummyHead;
        while(curr.next != null && curr.next.next != null) { // curr.next.val == curr.next.next.val要用到curr.next 和curr.next.next 因此这两个不能为null
            if(curr.next.val == curr.next.next.val) {
                int x = curr.next.val;
                while(curr.next != null && curr.next.val == x) { // 删除多个元素 用循环实现
                    curr.next = curr.next.next;
                }
            }else {
                curr = curr.next;
            }
        }
        return dummyHead.next;
    }
}