第83题

# Definition for singly-linked list.
# class ListNode:
#     def __init__(self, x):
#         self.val = x
#         self.next = None
#python3解法
class Solution:
    def deleteDuplicates(self, head: ListNode) -> ListNode:
    	'感觉思路最为清晰的解法'
        if head == None:
            return head  
        p = head
        while p.next:
            if p.val == p.next.val:
            	p.next = p.next.next
            else:
                p = p.next
        return head