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.
链接： http://leetcode.com/problems/remove-duplicates-from-sorted-list/
一刷，在考虑什么时候应该使用dummy node，什么时候不应该。感觉跟第一个元素有关，如果第一个元素肯定在输出中，可以不使用dummy node。
class Solution(object): def deleteDuplicates(self, head): """ :type head: ListNode :rtype: ListNode """ if not head: return head prev = head current = head.next while current: if prev.val == current.val: prev.next = current.next else: prev = prev.next current = current.next return head
83. Remove Duplicates from Sorted List
原文：http://www.cnblogs.com/panini/p/5586337.html