LeetCode-Remove Duplicates from Sorted List

#include <iostream>using namespace std;struct ListNode{    int val;    ListNode* next;};ListNode* deleteDuplicates(ListNode *head){    if(head==NULL)        return NULL;        ListNode* pNode=head;    ListNode* pHead=head;    while(pNode!=NULL)    {        while(pNode->next!=NULL&&pNode->val==pHead->val)        {            pNode=pNode->next;        }        if(pNode->val!=pHead->val)        {            pHead->next=pNode;            pHead=pNode;            pNode=pNode->next;        }        else//防止出现 1->1        {            pHead->next=NULL;            return head;        }            }    return head;}