Merge two sorted linked lists and return them as a new sorted list. The new list should be made by splicing together the nodes of the two given lists.
Examples
Example1
Inputl1 = [1,2,4], l2 = [1,3,4]
Output: [1, 1, 2, 3, 4, 4]
Example 2
Inputl1 = [], l2 = []
Output: []
Example 3
Inputl1 = [], l2 = [0]
Output: [0]
Constraints
The number of nodes in both lists is in the range [0, 50].
-100 <= Node.val <= 100
Both l1 and l2 are sorted in non-decreasing order.