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.
package pack;
class ListNode {
int val;
ListNode next;
ListNode(int x) { val = x; }
}
class Solution {
public ListNode mergeTwoLists(ListNode l1, ListNode l2) {
if(l1 == null)
return l2;
if(l2 ==