【second】Remove Duplicates from Sorted List

 

    ListNode *deleteDuplicates(ListNode *head) {
        // Note: The Solution object is instantiated only once and is reused by each test case.
        if(head==NULL)
            return NULL;
        
        ListNode* prev = head,*cur = head->next;
        while(cur)
        {
            ListNode* next = cur->next;
            if(cur->val==prev->val)
            {
                prev->next = next;
                delete cur;
            }else
                prev = cur;
            
            cur = next;
        }
        
        return head;
    }