题目意思：现在有一个已经排好顺序的链表，删除所有重复的节点，使每个节点都只出现一次！
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.
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/**
* Definition for singly-linked list.
* struct ListNode {
* int val;
* ListNode *next;
* ListNode(int x) : val(x), next(NULL) {}
* };
*/
//遍历链表，遍历过程中保存上一个节点的值如果与当前节点相同就删除
//维护两个指针，一个指向前一个节点，一个指向当前节点，相同就执行删除操作
class Solution {
public:
ListNode* deleteDuplicates(ListNode* head) {
if(head==NULL)
return NULL;
ListNode* preNode=NULL;
ListNode* curNode=head;
ListNode* delNode=NULL;
while(curNode)
{
if(preNode && preNode->val==curNode->val)
{
preNode->next=curNode->next;
delNode=curNode;
curNode=curNode->next;
delete delNode;
delNode=NULL;
continue;
}
preNode=curNode;
curNode=curNode->next;
}
return head;
}
};
<LeetCode OJ> 83. Remove Duplicates from Sorted List
原文：http://blog.csdn.net/ebowtang/article/details/50483226