Problem statement

https://binarysearch.com/problems/Add-Linked-Lists/

Solution

Equal to Leetcode 0002. Add Two Numbers.

Complexity

Time complexity is O(m + n) for time and O(max(m, n)) for space.

Code

class Solution:
    def solve(self, l1, l2):
        carry = 0
        head = curr = LLNode(0)

        while l1 or l2 or carry:
            d1, d2 = 0, 0
            if l1: 
                d1 = l1.val
                l1 = l1.next
            if l2: 
                d2 = l2.val
                l2 = l2.next
            carry, digit = divmod(d1 + d2 + carry, 10)
            curr.next = LLNode(digit)
            curr = curr.next
              
        return head.next