Naive Python Solution

• ``````class Solution(object):
c1, c2 = '', ''
while l1:
c1 += str(l1.val)
l1 = l1.next
while l2:
c2 += str(l2.val)
l2 = l2.next
num = str(int(c1) + int(c2))
dummy = ListNode(0)
c = dummy
for i in range(len(num)):
c.next = ListNode(num[i])
c = c.next
return dummy.next``````

• Maybe you shouldn't even consider this as a naive solution, because the spirit of this exercise is to show how large numbers are added when there is a bit limit (I think), therefore int(str(huge_number)) already fails the purpose

• @lucidsushi How did you know the "sprit of this excise"?

• @lilixu Someone told me about it when I shared them the original question (this one is part2). But you can imagine if a language had a method called add_two_linkedlist. Is there really a point to show the solution is return add_two_linkedlist(l1, l2)? You can check out the editoral comments for what the spirit of the question is https://leetcode.com/articles/add-two-numbers/

• @lilixu I agree with lucidsushi's opinion. According to the level of difficulty of this question, a medium level, one of test points should be how to manipulate singly linked lists to achieve the goal of summation of two lists; the other one point to check is how to use dfs idea to design your algorithm for this question. Your algorithm design is pretty easy, because all built-in Python functions you use in your code hide the test points. If you are preparing for technical interview, you should try not to use built-in Python functions in your solution. For easy level questions, you could use them.

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