删除链表中的重复节点

/*
struct ListNode {
    int val;
    struct ListNode *next;
    ListNode(int x) :
        val(x), next(NULL) {
    }
};
*/
class Solution {
public:
    ListNode* deleteDuplication(ListNode* pHead)
    {
        if(pHead==nullptr||pHead->next==nullptr)
        {
            return pHead;
        }
        ListNode *pPreNode=nullptr;
        ListNode *pNode=pHead;
        while(pNode!=nullptr)
        {
            ListNode *pNext=pNode->next;
            bool needDelete=false;
            if(pNext!=nullptr&&pNext->val==pNode->val)
                needDelete=true;
            if(!needDelete)
            {
                pPreNode=pNode;
                pNode=pNode->next;
            }
            else
            {
                int value=pNode->val;
                ListNode *pToBeDel=pNode;
                while(pToBeDel!=nullptr&&pToBeDel->val==value)
                {
                    pNext=pToBeDel->next;
                    delete pToBeDel;
                    pToBeDel=nullptr;
                    pToBeDel=pNext;
                }
                if(pPreNode==nullptr)
                    pHead=pNext;
                else
                    pPreNode->next=pNext;
                pNode=pNext;
            }
        }
        return pHead;
    }
};