Python实现"删除排序链表中的重复元素"的两种方法

给定一个有序链表，删除重复元素，保证每一个元素只出现一次

Example 1:

Input: 1->1->2
Output: 1->2

Example 2:

Input: 1->1->2->3->3
Output: 1->2->3

1：时间复杂度O(n），借助另外一个链表

def deleteDuplicates(self, head):
        """
        :type head: ListNode
        :rtype: ListNode
        """
        if not head:
            return None
        head_list = ListNode(0)     #头指针，不动
        cur_List = head_list        #当前指针
        cur_List.next = ListNode(head.val)    #指针移动
        cur_List = cur_List.next
        head = head.next      #head链表移动
        while head:           #遍历head链表
            if head.val != cur_List.val:
                cur_List.next =  ListNode(head.val)
                cur_List = cur_List.next
            head = head.next
        return head_list.next

2：时间复杂度O(n），不借助另外链表

def deleteDuplicates(self, head):
        """
        :type head: ListNode
        :rtype: ListNode
        """
        if not head:
            return None
        cur_List = head
        while cur_List.next:
            if cur_List.val == cur_List.next.val:
                cur_List.next = cur_List.next.next
            else:
                cur_List = cur_List.next
        return head

算法题来自:https://leetcode-cn.com/problems/remove-duplicates-from-sorted-list/description/