[leetcode]@python 83. Remove Duplicates from Sorted List

题目链接

https://leetcode.com/problems/remove-duplicates-from-sorted-list/

题目原文

Given a sorted linked list, delete all duplicates such that each element appear only once.

For example,
Given 1->1->2, return 1->2.
Given 1->1->2->3->3, return 1->2->3.

题目大意

删除链表中的重复元素，使每个元素只出现一次

解题思路

定义一个pre 和cur，1.当二者不等的时候pre.next=cur pre=pre.next 2.当相等的时候pre.next=cur.next 3.每步都是cur=cur.next

代码

# 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 head == None or head.next == None:
            return head
        ans = ListNode(0)
        ans.next = head
        pre = ans.next
        cur = ans.next

        while cur:
            if pre.val != cur.val:
                pre.next = cur
                pre = pre.next
            else:
                pre.next = cur.next
            cur = cur.next
        return ans.next