题解 | #删除有序链表中重复的元素-I#

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 deleteHelper(ListNode head){
        ListNode p1 = head;
        ListNode p2 = head.next;
        while(p2 != null){
            if(p2.val == head.val){
                p1.next = p2.next;
            }
            p1 = p1.next;
            p2 = p2.next;
        }
        return head;
    }
    public ListNode deleteDuplicates (ListNode head) {
        if(head == null || head.next == null) return head;
        ListNode new_head = deleteDuplicates(head.next);
        head.next = new_head;
        return deleteHelper(head);
    }
}