leetcode: merge tow sorted lists

gistfile1.cpp

    // https://oj.leetcode.com/problems/merge-two-sorted-lists/
    
    ListNode *mergeTwoLists(ListNode *l1, ListNode *l2) {
        ListNode dummy {0};
        ListNode** tail = &dummy.next;
        while (l1 && l2) {
            ListNode* tmp = nullptr;
            if (l1->val < l2->val) {
                tmp = l1; l1 = l1->next;
            } else {
                tmp = l2; l2 = l2->next;
            }
            *tail = tmp;
            tail = &tmp->next;
        }

        ListNode* tmp = l1 ? l1 : l2;
        while (tmp) {
            *tail = tmp;
            tmp = tmp->next;
            tail = &(*tail)->next;
        }
        return dummy.next;
    }