21. Merge Two Sorted Lists - cocoder39/coco39_LC GitHub Wiki

ListNode* mergeTwoLists(ListNode* l1, ListNode* l2) {
        ListNode dummy(0);
        ListNode* p = &dummy;
       
        while (l1 && l2) {
            if (l1->val <= l2->val) {
                p->next = l1;
                l1 = l1->next;
            }
            else {
                p->next = l2;
                l2 = l2->next;
            }
            p = p->next;
        }
        l1 ? p->next = l1 : p->next = l2;
        return dummy.next;
    }