remove-duplicates-from-sorted-list

题目：

Given a sorted linked list, delete all duplicates such that each element appear only once.
For example,
Given1->1->2, return1->2.
Given1->1->2->3->3, return1->2->3.

程序：

class Solution {
public:
ListNode *deleteDuplicates(ListNode *head) {
if(head==NULL)
return head;
if(head->next==NULL)
return head;
ListNode *p=head,*q=head->next;

    while(q)    {        if(q->val==p->val)        {            q=p->next->next;            p->next=q;        }        else        {            p=q;            q=q->next;        }    }    return head;}

};