Merge Two sorted Linked lists leet code

 # 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, list1: Optional[ListNode], list2: Optional[ListNode]) -> Optional[ListNode]:

        """To merge two sorted linked list first have to create dummynode and made this node as tail """

        dummy=ListNode()

        tail=dummy

        """Now check the value in list1 and list2 if value of list 1 is smaller it should made as next to dummy tail else list2 value should made  tail to dummy tail. after making now head node of list change to its next node"""

        while list1 and list2:

            

            if list1.val<list2.val:

                tail.next=list1

                list1=list1.next

            else :

                tail.next=list2

                list2=list2.next

            tail=tail.next

        if list1:

            tail.next=list1

        elif list2:

            tail.next=list2

            

        return dummy.next