力扣第8天——删除链表中重复元素

此题设置双指针遍历链表，当前指针指向None叫停即可：

# Definition for singly-linked list.
# class ListNode:
#     def __init__(self, x):
#         self.val = x
#         self.next = None

class Solution:
    def deleteDuplicates(self, head: ListNode) -> ListNode:
        if head==None or head.next==None:
            return head
        pre=head
        be=head.next
        while pre.next!=None:
            if be.val==pre.val:
                be=be.next
                pre.next=be
            else:
                pre=pre.next
                be=be.next
        return head