题解 | #删除链表中重复的结点#

#     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 pHead ListNode类 
# @return ListNode类
#
class Solution:
    def deleteDuplication(self , pHead: ListNode) -> ListNode:
        # write code here
        ppre = ListNode(-1)
        pre = ListNode(-1)
        ppre.next = pre
        pre.next = pHead  # 是为了保证输入只有1个元素时，可以不执行下面的while循环，直接进行return
        while pHead and pHead.next:  # pHead.next是为了保证输入只有1个元素时，可以不用执行本while循环，因为如果执行的话也是pre指向空
            if pHead.next and pHead.val != pHead.next.val:
                pre.next = pHead
                pre = pre.next
                pHead = pHead.next
            else:
                val = pHead.val
                while pHead and pHead.val == val:
                    pHead = pHead.next
                pre.next = pHead
        return ppre.next.next