[Power button - small daily practice] 2. The two numbers together (python)

2. The two numbers together

Topic links: https://leetcode-cn.com/problems/add-two-numbers/

Title Description

We are given two non-null linked list is used to represent two non-negative integer. Among them, in accordance with their respective median is the reverse of the way storage, and they each node can store only one digit.

If we add up these two numbers, it will return a new list and to represent them.

You can assume that in addition to the numbers 0, these two numbers will not begin with 0.

Examples

Input : (2 -> 4 -> 3) + (5 -> 6 -> 4)
Output : 7 -> 0 -> 8
Cause : 342 + 465 = 807

Input : (0) + (0)
Output : 0
Reason : 0 + 0 = 0

Input : (9 -> 8) (1) +
Output : 0 -> 9
Cause : 89 + 1 = 90

# Definition for singly-linked list.
# class ListNode:
#     def __init__(self, x):
#         self.val = x
#         self.next = None

class Solution:
    def addTwoNumbers(self, l1: ListNode, l2: ListNode) -> ListNode:
        
        result = ListNode(0)
        curr = result
        flag = 0
        while l1 or l2:
            temp1 = 0
            temp2 = 0
            if l1:
                temp1 =  l1.val
                l1 = l1.next
            if l2:
                temp2 = l2.val
                l2 = l2.next
            temp = temp1 + temp2 + flag
            curr.next = ListNode(temp%10)
            curr = curr.next
            flag = temp // 10
        
        if flag != 0:
            curr.next = ListNode(1)

        return result.next if result.next else result