book-solution-merge-two-sorted-lists.java

public static final ListNode<Integer> mergeTwoSortedLists(ListNode<Integer> L1, ListNode<Integer> L2) {
        System.out.printf(">>> Merging %s and %s", L1, L2);
        System.out.println();
        ListNode<Integer> dummyHead = new ListNode<>(new Random().nextInt(), (ListNode<Integer>) null);
        ListNode<Integer> current = dummyHead;
        ListNode<Integer> p1 = L1;

        ListNode<Integer> p2 = L2;
        while (p1.getNext() != null && p2.getNext() != null) {
            if (p1.getData() <= p2.getData()) {
                current.setNext(p1);
                p1.getNext();

                p1 = p1.getNext();
            } else {
                current.setNext(p2);
                p2 = p2.getNext();
            }

            current = current.getNext();
        }

        current.setNext(p1 != null? p1 : p2);

        System.out.printf("<<< Merge result : %s", dummyHead.getNext());
        System.out.println();
        return dummyHead.getNext();
    }