21. Merge Two Sorted Lists(Java)

Merge two sorted linked lists and return it as a new list. The new list should be made by splicing together the nodes of the first two lists.

public class Solution {    public ListNode mergeTwoLists(ListNode l1, ListNode l2) {        if (l1 == null) return l2;        if (l2 == null) return l1;        if (l1.val <= l2.val) {            l1.next = mergeTwoLists(l1.next, l2);            return l1;        } else {            l2.next = mergeTwoLists(l2.next, l1);            return l2;        }    }}