reverse a list

reverse a list:

//iterative
ListNode* reverse(ListNode* head) {
    if (head == NULL || head->next == NULL) return head;
    ListNode dummy(0);
    dummy.next = head;
    head = &dummy;
    ListNode* cur = head->next;
    while(cur->next != NULL) {
        ListNode* tmp = cur->next;
        cur->next = tmp->next;
        tmp->next = head->next;
        head->next = tmp;
    }
    return head->next;
}

//recursive
ListNode* reverse(ListNode* head) {
    if (head == NULL || head->next == NULL) return head;
    ListNode* next=head->next;
    ListNode* newhead=    reverse(next);
    next->next=head;
    head->next=NULL;
    return newhead;   

}