Problem: Merge Two Sorted Lists

Statement

Given the heads of two sorted linked lists, list1 and list2, merge them into a single sorted linked list by splicing together the nodes from both input lists.

Return the head of the resulting merged linked list.

Note: Both list1 and list2 are sorted in non-decreasing order.

Constraints:

• The number of nodes in each list is in the range $[0, 50]$.

• $-100 \leq$ ...