leetcode-Remove Duplicates from Sorted List

Difficulty: Easy

Given a sorted linked list, delete all duplicates such that each element appear onlyonce.

For example,
Given 1->1->2, return 1->2.
Given 1->1->2->3->3, return 1->2->3.

/** * 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){        ListNode *left=head,*right=head;        while(right){            bool dupli=false;            while(right->next&&right->next->val==right->val){                right=right->next;                dupli=true;            }            if(dupli)                left->next=right->next;            left=left->next;            right=right->next;        }        return head;    }};