Leetcode 21. Merge Two Sorted Lists

# Runtime: 40 ms, faster than 33.20% of Python3 online submissions for Merge Two Sorted Lists.
# Memory Usage: 13.8 MB, less than 6.61% of Python3 online submissions for Merge Two Sorted Lists.

class Solution:
    def mergeTwoLists(self, l1: ListNode, l2: ListNode) -> ListNode:
        if l1 and l2:
            if l1.val > l2.val:
                l1, l2 = l2, l1
            l1.next = self.mergeTwoLists(l1.next, l2)
        return l1 or l2

https://leetcode.com/problems/merge-two-sorted-lists/