Python3 代码

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

class Solution(object):
    def deleteDuplication(self, head):
        """
        :type head: ListNode
        :rtype: ListNode
        """

        ln = ListNode(0);
        ln.next = head;

        p = ln;

        while p.next != None :
            q = p.next
            hasDup = False

            while q.next != None and q.val == q.next.val:
                q.val = q.next.val
                q.next = q.next.next
                hasDup = True

            if hasDup and q.next != None:
                q.val = q.next.val
                q.next = q.next.next
                p.next = q
            elif hasDup and q.next == None:
                p.next = None
                break
            else:
                p = q;

        return ln.next