删除链表中重复节点（设一个前驱节点找到重复节点后删除）

class Solution {
public:
    ListNode* deleteDuplication(ListNode* pHead)
    {
        ListNode *vhead = new ListNode(-1);
        vhead->next = pHead;
        ListNode *pre = vhead, *cur = pHead;        
        while (cur) {
            if (cur->next && cur->val == cur->next->val) {
                cur = cur->next;
                while (cur->next && cur->val == cur->next->val) {
                    cur = cur->next;
                }
                cur = cur->next;
                pre->next = cur;
            }
            else {
                pre = cur;
                cur = cur->next;
            }
        }
        return vhead->next;
    }
};