题目：
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.
代码：
1 # Definition for singly-linked list. 2 # class ListNode: 3 # def __init__(self, x): 4 # self.val = x 5 # self.next = None 6 7 class Solution: 8 # @param head, a ListNode 9 # @return a ListNode 10 def deleteDuplicates(self, head): 11 if head is None or head.next is None: 12 return head 13 14 dummyhead = ListNode(0) 15 dummyhead.next = head 16 p = dummyhead.next 17 18 while p.next is not None: 19 if p.val == p.next.val: 20 p.next = p.next.next 21 else: 22 p = p.next 23 24 return dummyhead.next
思路：
设立虚表头dummyhead
遇上val不同的，再执行 p=p.next；否则指针p不动，只是p.next变化。
leetcode 【 Remove Duplicates from Sorted List 】 python 实现
原文：http://www.cnblogs.com/xbf9xbf/p/4186734.html