原题链接：https://leetcode.com/problems/remove-duplicates-from-sorted-list/
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.
思路：
算法：
【Leetcode】Remove Duplicates from Sorted List
原文：http://blog.csdn.net/yeqiuzs/article/details/51606459