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) {
        if(head == null || head.next == null) return head;
        ListNode slow = head, fast = head.next;
        while(fast != null){
            if(slow.val == fast.val){
                fast = fast.next;
            }else{
                slow.next = fast;
                fast = fast.next;
                slow = slow.next;
            }     
        }
        slow.next = null;
        return head;
    }
}