sum_list_lc2.py

# 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
# Explanation: 342 + 465 = 807.


class LinkedList(object):
    """Simple linked list class."""

    def __init__(self, val):
        """."""
        self.next = None
        self.val = val


def sum_list(l1, l2):
    """Get the sum of lists (reverse) digitize return same output format as input (reverse list)."""
    dummy = LinkedList(None)
    temp = dummy  # temp will be iterating node
    carry = 0

    while l1 or l2 or carry:
        if l1:
            carry += l1.val
            l1 = l1.next
        if l2:
            carry += l2.val
            l2 = l2.next
        temp.next = LinkedList(carry % 10)  # will be single place digit
        carry /= 10  # will be double place digit
        temp = temp.next  # creating result list
    return dummy.next  # dummy still points to start of result list