Remove Duplicates from Sorted List II

Remove Duplicates from Sorted List II

Given a sorted linked list, delete all nodes that have 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.

代码：

ListNode* deleteDuplicates(ListNode* head){    if(head == NULL || head->next == NULL) return head;    ListNode *res = new ListNode(-1);    res->next = head;    ListNode *r = res, *p = head;    while(p != NULL)    {        bool same = false;        while(p->next != NULL && p->val == p->next->val)        {            same = true;            p = p->next;        }        if(same == true)        {            p = p->next;            continue;        }        r->next = p;        r = r->next;        p = p->next;    }    r->next = p;    return res->next;}