Example 1:
Input: list1 = [1,2,4], list2 = [1,3,4]
Output: [1,1,2,3,4,4]
Example 2:
Input: list1 = [], list2 = []
Output: []
Example 3:
Input: list1 = [], list2 = [0]
Output: [0]
You are given the heads of two sorted linked lists list1 and list2.
Merge the two lists into one sorted linked list and return the head of the new sorted linked list.
The new list should be made up of nodes from list1 and list2.
The number of nodes in both lists is in the range [0, 50].-100 <= Node.val <= 100Both list1 and list2 are sorted in non-decreasing order.