草稿暂存

class Solution {public:    ListNode *deleteDuplicates(ListNode *head) {        if (head == NULL)            return NULL;                    bool isDup;        ListNode *pos = head, *next_pos = head->next;                if (next_pos == NULL)            return head;                    ListNode *pre_pos = new ListNode(0);        ListNode *new_head = pre_pos;        pre_pos->next = head;                while (next_pos != NULL)        {            isDup = false;            while (next_pos != NULL && pos->val == next_pos->val)            {                isDup = true;                next_pos = next_pos->next;            }            if (isDup)            {                pre_pos->next = next_pos;                pos = next_pos;            }            else            {                pre_pos = pre_pos->next;                pos = pos->next;            }            next_pos = next_pos->next;        }        return new_head->next;    }};