leetcode ——83. 删除排序链表中的重复元素

# 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 not head:
            return
        p=head
        q=head.next
        while q:
            if p.val==q.val:
                q=q.next
                p.next=q
            else:
                p=q
                q=q.next
        return head