DataStructuresPython/Merge Two Sorted Linked List.py at master · amod26/DataStructuresPython · GitHub

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# Definition for singly-linked list.
# class ListNode:
#     def __init__(self, x):
#         self.val = x
#         self.next = None


class Solution:
    def mergeTwoLists(self, l1: ListNode, l2: ListNode) -> ListNode:
        head = ListNode(0)
        temp = head

        while l1 and l2:
            if l1.val < l2.val:
                temp.next = l1
                l1 = l1.next
            else:
                temp.next = l2
                l2 = l2.next
            temp = temp.next

        while l1:
            temp.next = l1
            l1 = l1.next
            temp = temp.next
        while l2:
            temp.next = l2
            l2 = l2.next
            temp = temp.next

        head = head.next
        return head

## Recrusion
   def mergeTwoLists(self, l1: ListNode, l2: ListNode) -> ListNode:
        if l1 is None:
            return l2
        elif l2 is None:
            return l1
        elif l1.val < l2.val:
            l1.next = self.mergeTwoLists(l1.next, l2)
            return l1
        else:
            l2.next = self.mergeTwoLists(l1, l2.next)
            return l2