题解 | #牛群排列去重#

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 deleteDuplicates (ListNode head) {
        // write code here
       Set<Integer> set = new HashSet<>();
       while(head != null){
        set.add(head.val);
        head = head.next;
       }

       ListNode result = new ListNode(-1);
       ListNode cur = result;
       for(Integer i: set){
            cur.next = new ListNode(i);
            cur = cur.next;
       }
       return result.next;
    }
}