Add Two Numbers

add_two_numbers.py

"""
Description:
You are given two non-empty linked lists representing two non-negative integers.
The digits are stored in reverse order and each of their nodes contain a single
digit. Add the two numbers and return it as a linked list.

You may assume the two numbers do not contain any leading zero, except the number 0 itself.

Example:
Input: (2 -> 4 -> 3) + (5 -> 6 -> 4)
Output: 7 -> 0 -> 8 --- 342 + 465 = 807
"""
class ListNode:
    def __init__(self, x):
        self.val = x
        self.next = None

def addTwoNumbers(l1, l2):
    """
    :type l1: ListNode
    :type l2: ListNode
    :rtype: ListNode
    """
    if not l1 or not l2:
        return l1 or l2
    head = l1
    carry = 0
    while l1 and l2:
        carry, rem = divmod(l1.val + l2.val + carry, 10)
        l1.val = rem
        cur, l1, l2 = l1, l1.next, l2.next
    cur.next = l1 or l2
    print('carry', carry)
    while carry != 0:
        if not cur.next:
            cur.next = ListNode(carry)
            break
        else:
            carry, rem = divmod(cur.next.val + carry, 10)
            cur.next.val = rem
            cur = cur.next
    return head