2.add-two-numbers.py

#
# @lc app=leetcode id=2 lang=python3
#
# [2] Add Two Numbers
#
from typing import *
from lcimports import *
# @lc code=start
# Definition for singly-linked list.
# class ListNode:
#     def __init__(self, val=0, next=None):
#         self.val = val
#         self.next = next
class Solution:
    def addTwoNumbers(self, l1: Optional[ListNode], l2: Optional[ListNode]) -> Optional[ListNode]:
        carry = 0
        dummy = head = ListNode()
        while l1 or l2:
            v1 = l1.val if l1 else 0
            v2 = l2.val if l2 else 0
            s = v1 + v2 + carry
            carry = s // 10
            head.next = ListNode(s % 10)
            head = head.next
            if l1: l1 = l1.next
            if l2: l2 = l2.next
        if carry:
            head.next = ListNode(carry)
        return dummy.next

# @lc code=end