删除链表中重复的结点

ListNode* deleteDuplication(ListNode* pHead)    {        if ( NULL == pHead || NULL == pHead->next )            return pHead;                ListNode* p1 = pHead;        ListNode* p2 = pHead->next;        ListNode* pPrev = pHead;        ListNode* pNewHead = pHead;                if ( p1->val == p2->val ){            pPrev = NULL;            pNewHead = NULL;        }                while ( 1 ){            if ( p1->val == p2->val ){//在这个大逻辑中，删除节点                while ( p1->val == p2->val ){                    if ( NULL == p2->next ){                        if ( NULL == pNewHead )                            return NULL;                        else{                            pPrev->next = NULL;                            delete p1;                            delete p2;                            return pNewHead;                        }                    }                    else{                        ListNode* tmp = p2;                        p2 = p2->next;                        delete tmp;                        tmp = NULL;                    }                }                if ( NULL == pNewHead )pNewHead = pPrev = p2;delete p1;p1 = p2;if ( NULL == p2->next ){if ( pPrev != p2 )pPrev->next = p2;return pNewHead;}else{p2 = p2->next;if ( p1->val == p2->val ){if ( p1 == pNewHead ){pPrev = NULL;pNewHead = NULL;}}}}else{if ( p1 != pPrev )pPrev->next = p1;pPrev = p1;p1 = p1->next;if ( NULL != p2->next )p2 = p2->next;else{pPrev->next = p2;return pNewHead;}}        }    }

在一个有序的链表中，存在重复的结点，请删除该链表中重复的结点，重复的结点不保留，返回链表头指针。 

例如，链表1->2->3->3->4->4->5 处理后为 1->2->5