LeetCode - Refresh - Partition List

I am lazy so I did not clear the two dynamic allowcated .

/**
 * Definition for singly-linked list.
 * struct ListNode {
 *     int val;
 *     ListNode *next;
 *     ListNode(int x) : val(x), next(NULL) {}
 * };
 */
class Solution {
public:
    ListNode *partition(ListNode *head, int x) {
        if (!head || !head->next) return head;
        ListNode *ahead = new ListNode(0);
        ListNode *bhead = new ListNode(0);
        ListNode *atail = ahead, *btail = bhead;
        while (head) {
            if (head->val < x) {
                atail->next = head;
                atail = atail->next;
            } else {
                btail->next = head;
                btail = btail->next;
            }
            head = head->next;
        }
        atail->next = bhead->next;
        btail->next = NULL;
        return ahead->next;
    }
};