链表_leetcode82

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

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

        if not head or not head.next:
            return head

        dummyHead = ListNode(0)
        dummyHead.next = head
        pre = dummyHead

        curNode = head
        nextNode = curNode.next
        curVal = curNode.val
        unique = True

        while curNode and nextNode:

            if curNode.val == curVal and nextNode.val == curVal:
                unique = False
                curNode = nextNode
                nextNode = nextNode.next
                continue

            if curNode.val == curVal and nextNode.val != curVal and not unique:
                curNode = nextNode
                nextNode = nextNode.next
                curVal = curNode.val
                unique = True
                continue

            else:
                pre.next = curNode
                pre = pre.next

                curNode = nextNode
                nextNode=nextNode.next
                curVal = curNode.val
                unique = True

        if curNode.val == curVal and not unique:
            pre.next = None

        if curNode.val == curVal and  unique:
            pre.next = curNode


        return dummyHead.next