Merge two ordered lists --python

Title Description

The two ordered lists into a new sorted list and return. The new list is by all nodes in a given mosaic composed of two lists.

Example:

Input: 1-> 2-> 4, 1-> 3-> 4
Output: 1-> 1-> 2-> 3-> 4-> 4

Recursive solution

class Solution:
    def mergeTwoLists(self, l1: ListNode, l2: ListNode) -> ListNode:
        if (not l1) or (not l2):
            return l1 or l2
        if l1.val < l2.val:
            l1.next = self.mergeTwoLists(l1.next,l2)
            return l1
        else:
            l2.next = self.mergeTwoLists(l1,l2.next)
            return l2

operation result

Non-recursive solution

class Solution:
    def mergeTwoLists(self, l1: ListNode, l2: ListNode) -> ListNode:
        head = ListNode(None)
        p = head
        while l1 and l2:
            if l1.val <= l2.val:
                p.next = l1
                l1 = l1.next
            else:
                p.next = l2
                l2 = l2.next
            p = p.next
        if not l1:
            p.next = l2
        else:
            p.next = l1
        return head.next

operation result