83.移除链表重复项

Remove Duplicates from Sorted List

问题描述：

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.

测试代码：

/**
 * Definition for singly-linked list.
 * struct ListNode {
 *     int val;
 *     ListNode *next;
 *     ListNode(int x) : val(x), next(NULL) {}
 * };
 */
class Solution {
public:
    ListNode* deleteDuplicates(ListNode* head) {
        if(!head)
            return head;
        ListNode* p = head;
        ListNode* pos = head->next;
        int v = head->val;
        while(pos)
        {
            if(pos->val==v)
            {
                p->next = pos->next;
                pos = pos->next;
            }else{
                v = pos->val;
                pos = pos->next;
                p = p->next;
            }
        }
        return head;
    }
};

性能：