leetcode82

import collections
class Solution:
    def constructLink(self,lists):
        n = len(lists)
        if n == 0:
            return None
        if n == 1:
            return ListNode(lists[0])
        
        head = ListNode(lists[-1])
        for i in range(n-2,-1,-1):
            cur = ListNode(lists[i])
            cur.next = head 
            head = cur
        return head
    
    def deleteDuplicates(self, head: ListNode) -> ListNode:
        dic = collections.OrderedDict()#使用有序字典
        while head != None:
            if head.val not in dic:
                dic[head.val] = 1
            else:
                dic[head.val] += 1
            head = head.next
        lists = []
        for k,v in dic.items():#保序
            if v == 1:
                lists.append(k)#只保留出现一次的节点值
        return self.constructLink(lists)#使用list建立链表