sol.cpp

#include <iostream>

using namespace std;

struct ListNode
{
    int val;
    ListNode *next;
    ListNode() : val(0), next(nullptr) {}
    ListNode(int x) : val(x), next(nullptr) {}
    ListNode(int x, ListNode *next) : val(x), next(next) {}
};

class Solution
{
public:
    ListNode *addTwoNumbers(ListNode *l1, ListNode *l2)
    {
        ListNode *dummy = new ListNode(0);
        ListNode *cur = dummy;
        int carry = 0;

        while (l1 != nullptr || l2 != nullptr)
        {
            int x = (l1 != nullptr) ? l1->val : 0;
            int y = (l2 != nullptr) ? l2->val : 0;
            int sum = carry + x + y;

            carry = sum / 10;
            cur->next = new ListNode(sum % 10);
            cur = cur->next;

            if (l1 != nullptr)
                l1 = l1->next;
            if (l2 != nullptr)
                l2 = l2->next;
        }

        if (carry > 0)
        {
            cur->next = new ListNode(carry);
        }

        return dummy->next;
    }
};

int main()
{
    // call the fn here
    return 0;
}