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 head:
            p_nod_cur = head
        else:
            return head
		# 使用双指针遍历链表
        while p_nod_cur.next :
            p_nod_next = p_nod_cur.next
            if p_nod_cur.val == p_nod_next.val:# 如果相等，抛去后一个指针
                if p_nod_next.next:
                    p_nod_cur.next = p_nod_next.next
                else:							# 如果不相等，后移被比较指针
                    p_nod_cur.next = None
                    return head
            else:
                p_nod_cur = p_nod_cur.next
        return head