class Partition {
public:
    ListNode* partition(ListNode* pHead, int x) {
        struct ListNode*LessHead,*LessTail,*GreaterHead,*GreaterTail;
        LessTail = LessHead = (struct ListNode*)malloc(sizeof(struct ListNode));
        GreaterTail = GreaterHead = (struct ListNode*)malloc(sizeof(struct ListNode));
        struct ListNode* cur = pHead;
        
        while(cur)
        {
if(cur->val < x)
        {
            LessTail->next = cur;
            LessTail = cur;
            cur = cur->next;
        }
        else
        {
            GreaterTail->next = cur;
            GreaterTail = cur;
            cur = cur->next;
        }
        }
        LessTail->next  =  GreaterHead->next;
        GreaterTail->next = NULL;
        struct ListNode* list = LessHead->next;
        free(LessHead);
        free(GreaterHead);
        return list;



    }
};