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Add two numbers - linked list representation of numbers

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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.

class Solution:
    def addTwoNumbers(self, l1: ListNode, l2: ListNode) -> ListNode:
        dummyHead = ListNode(0)
        tail = dummyHead
        carry = 0

        while l1 is not None or l2 is not None or carry != 0:
            digit1 = l1.val if l1 is not None else 0
            digit2 = l2.val if l2 is not None else 0

            sum = digit1 + digit2 + carry
            digit = sum % 10
            carry = sum // 10

            newNode = ListNode(digit)
            tail.next = newNode
            tail = tail.next

            l1 = l1.next if l1 is not None else None
            l2 = l2.next if l2 is not None else None

        result = dummyHead.next
        dummyHead.next = None
        return result

Posted by Jamie Meyer 3 months ago

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