Stealth Coach

Add Two Numbers Solution

My Thoughts:

1. Create a dummy node to build the result list.
2. Traverse both lists, summing digits and managing carry.
3. Append new nodes with the correct digit values.
4. Return the resulting linked list.

class Solution:
    def addTwoNumbers(self, l1: Optional[ListNode], l2: Optional[ListNode]) -> Optional[ListNode]:
        dummy = ListNode(0)
        current = dummy
        carry = 0
        
        while l1 or l2 or carry:
            v1 = l1.val if l1 else 0
            v2 = l2.val if l2 else 0
            total = v1 + v2 + carry
            
            carry = total // 10
            current.next = ListNode(total % 10)
            current = current.next
            
            l1 = l1.next if l1 else None
            l2 = l2.next if l2 else None
        
        return dummy.next