题解 | #删除有序链表中重复的元素-I#

using System;
using System.Collections.Generic;

/*
public class ListNode
{
    public int val;
    public ListNode next;

    public ListNode (int x)
    {
        val = x;
    }
}
*/

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 deleteDuplicates (ListNode head) {
        // write code here
        if (head == null || head.next == null) return head;
        SortedSet<int> set = new SortedSet<int>();
        ListNode t = head;
        while (t != null) {
            if (!set.Contains(t.val))
                set.Add(t.val);
            t = t.next;
        }
        //辅助头结点
        ListNode res = new ListNode(-1);
        ListNode tail = res;
        foreach (var item in set) {
            ListNode newNode = new ListNode(item);
            tail.next = newNode;
            tail = newNode;
        }
        return res.next;
    }
}