Add two numbers represented by Linked list

Intuition

• gyan_pelo
• To add two numbers, traversal of Linked List will be done, both Linked List have to be of same length, inmaintaince_phase the loop should continue if one of the Linked List has element so use or condition in while loop to check if either of them is valid.

Code

class ListNode:
    def __init__(self, val=0, next=None):
        self.val = val
        self.next = next
 
def addTwoNumbers(l1: ListNode, l2: ListNode) -> ListNode:
    carry = 0
    dummy = ListNode()
    curr = dummy
    while l1 or l2 or carry:
        val1 = l1.val if l1 else 0
        val2 = l2.val if l2 else 0
        total = val1 + val2 + carry
        carry = total // 10
        curr.next = ListNode(total % 10)
        curr = curr.next
        l1 = l1.next if l1 else None
        l2 = l2.next if l2 else None
    return dummy.next
 
# Example usage
l1 = ListNode(2, ListNode(4, ListNode(3)))
l2 = ListNode(5, ListNode(6, ListNode(4)))
result = addTwoNumbers(l1, l2)
# The result should be 7 -> 0 -> 8, which represents the number 807.