merge-two-sorted-lists

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

Example:

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

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

class Solution:
    def mergeTwoLists(self, l1, l2):
        """
        :type l1: ListNode
        :type l2: ListNode
        :rtype: ListNode
        """
        if l1==None:
            return l2
        if l2==None:
            return l1
        start_node=ListNode(0)
        head=start_node
        length=2
        test=l1
        while test.next!=None:
            length+=1
            test=test.next
        test=l2
        while test.next!=None:
            length+=1
            test=test.next
        count=0
        flag_l1=False
        flag_l2=False
        while count<length:
            if count==0:
                if l1.val<l2.val:
                    start_node.val=l1.val
                    
                    if l1.next!=None:
                        l1=l1.next
                    else:
                        flag_l2=True
                else:
                    start_node.val=l2.val
                    if l2.next!=None:
                        l2=l2.next
                    else:
                        flag_l1=True
                count+=1
            else:
                
                if l1.val<l2.val:
                    value=l1.val
                    if l1.next!=None:
                        l1=l1.next
                    else:
                        flag_l2=True
                else:
                    value=l2.val
                    if l2.next!=None:
                        l2=l2.next
                    else:
                        flag_l1=True
                tmp_node=ListNode(value)
                start_node.next=tmp_node
                start_node=tmp_node
                count+=1
            if flag_l1:
                while l1.next!=None:
                    value=l1.val
                    tmp_node=ListNode(value)
                    start_node.next=tmp_node
                    start_node=tmp_node
                    l1=l1.next
                    count+=1
                value=l1.val
                tmp_node=ListNode(value)
                start_node.next=tmp_node
                count+=1
            if flag_l2:
                while l2.next!=None:
                    value=l2.val
                    tmp_node=ListNode(value)
                    start_node.next=tmp_node
                    start_node=tmp_node
                    l2=l2.next
                    count+=1
                value=l2.val
                tmp_node=ListNode(value)
                start_node.next=tmp_node
                count+=1
        return head
       
            
        
Solution:
https://leetcode.com/problems/merge-two-sorted-lists/