Java实现删除排序链表中的重复元素的方法

/**
 * Definition for singly-linked list.
 * public class ListNode {
 *   int val;
 *   ListNode next;
 *   ListNode(int x) { val = x; }
 * }
 */
class Solution {
   public ListNode deleteDuplicates(ListNode head) {
    if(head == null || head.next == null){
      return head;
    }
    head.next = deleteDuplicates(head.next);
    if(head.val == head.next.val) head = head.next;
    return head;
  }
}