[LeetCode82] Remove duplicates from Sorted List II

Topic:

Given a sorted linked list, delete all nodes that has duplicate numbers, leaving only distinct numbers from the Original list.

For example,
Given 1->2->3->3->4->4->5 , return 1->2->5 .
Given 1->1->1->2->3 , return 2->3 .

Category: Linked List

Code: maintaining two pointers ptr,pre

1 /**2 * Definition for singly-linked list.3 * struct ListNode {4 * int val;5 * ListNode *next;6 * ListNode (int x): Val (x), Next (NULL) {}7  * };8  */9 classSolution {Ten  Public: Onelistnode* Deleteduplicates (listnode*head) { A         if(!head) -             returnhead; -         if(Head &&!head->next) the             returnhead; -ListNode *newhead =NewListNode (Head->val-1); -Newhead->next =head; -ListNode *pre =Newhead; +ListNode *ptr =Newhead; -          while(head) +         { A             if(Pre->val! = Head->val && (!head->next | | Head->val! = head->next->val)) at             { -Ptr->next =head; -PTR = ptr->Next; -             } -Pre =head; -Head = head->Next; in         } -Ptr->next =NULL; to          +         returnNewhead->Next; -     } the};

[LeetCode82] Remove duplicates from Sorted List II