add-two-numbers-ii.py

# 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]:
        num1 = ""
        while l1:
            num1 += str(l1.val)
            l1 = l1.next
        num2 = ""
        while l2:
            num2 += str(l2.val)
            l2 = l2.next
        
        result = str(int(num1) + int(num2))
        head = ListNode(result[0])
        result = result[1: ]
        temp = head
        while result:
            temp.next = ListNode(result[0])
            result = result[1 : ]
            temp = temp.next
                        
        return head