feat(work): implement correct addTwoNumbers algorithm for linked list addition

work/1/Medium/Linked List/2.add-two-numbers.py

@@ -53,9 +53,18 @@ class Solution:
     def addTwoNumbers(
         self, l1: Optional[ListNode], l2: Optional[ListNode]
     ) -> Optional[ListNode]:
-        head = ListNode()
+
+        dummy = ListNode()
         carry = 0
-        l1curr = head
-        l2curr = head
-        while head:
-            l1.val + l2.val
+        curr = dummy
+        while l1 or l2 or carry:
+            s = (l1.val if l1 else 0) + (l2.val if l2 else 0) + carry
+            carry, val = divmod(s, 10)
+
+            curr.next = ListNode(val)
+            curr = curr.next
+
+            l1 = l1.next if l1 else None
+            l2 = l2.next if l2 else None
+
+        return dummy.next