Add Two Numbers.py

# https://leetcode.com/problems/add-two-numbers/
# Hak Soo Kim
# 12/22/2021

# Definition for singly-linked list.
# class ListNode(object):
#     def __init__(self, val=0, next=None):
#         self.val = val
#         self.next = next
class Solution(object):
    def addTwoNumbers(self, l1, l2):
        tenth = 0
        head = prevNode = None
        while (tenth == 1 or l1 != None or l2 != None):
            sumVal = tenth
            if (l1 != None):
                sumVal += l1.val
                l1 = l1.next
            if (l2 != None):
                sumVal += l2.val
                l2 = l2.next
            tenth = sumVal / 10
            sumVal = sumVal % 10
            if (prevNode == None):  # first node
                prevNode = ListNode(sumVal, None)
                head = prevNode
            else:  # not first node
                newNode = ListNode(sumVal, None)
                prevNode.next = newNode
                newNode.val = sumVal
                prevNode = newNode
        return head

# 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 contains a single digit. Add the two numbers and return the sum as a linked list.
#
# You may assume the two numbers do not contain any leading zero, except the number 0 itself.
# Example 1:
#
# Input: l1 = [2,4,3], l2 = [5,6,4]
# Output: [7,0,8]
# Explanation: 342 + 465 = 807.
#
# Example 2:
#
# Input: l1 = [0], l2 = [0]
# Output: [0]
# Example 3:
#
# Input: l1 = [9,9,9,9,9,9,9], l2 = [9,9,9,9]
# Output: [8,9,9,9,0,0,0,1]
#
# Constraints:
#
# The number of nodes in each linked list is in the range [1, 100].
# 0 <= Node.val <= 9
# It is guaranteed that the list represents a number that does not have leading zeros.