"""

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

Example 1:

Input: l1 = [1,2,4], l2 = [1,3,4]

Output: [1,1,2,3,4,4]

Example 2:

Input: l1 = [], l2 = []

Output: []

Example 3:

Input: l1 = [], 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.

"""

# Definition for singly-linked list.

class ListNode:

def __init__(self, val=0, next=None):

self.val = val

self.next = next

class Solution:

def mergeTwoLists(self, l1: ListNode, l2: ListNode) -> ListNode:

if l1 is None:

return l2

if l2 is None:

return l1

if l1.val < l2.val:

l1.next = self.mergeTwoLists(l1.next, l2)

return l1

else:

l2.next = self.mergeTwoLists(l1, l2.next)

return l2