题解 | #牛群排列去重#

# class ListNode:
#     def __init__(self, x):
#         self.val = x
#         self.next = None
#
# 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
#
class Solution:
    def deleteDuplicates(self , head: ListNode) -> ListNode:
        # write code here
        if not head or not head.next:
            return head

        p = head
        q = head.next

        while q:
            if p.val == q.val:
                p.next = q.next
                q = q.next
            else:
                p = q
                q = q.next

        return head