2.cpp

#include <vector>
#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) {}
};

// Cria uma lista encadeada a partir de um vetor
ListNode *createList(const vector<int> &values)
{
    ListNode *head = nullptr;
    ListNode *tail = nullptr;

    for (int val : values)
    {
        ListNode *newNode = new ListNode(val);
        if (head == nullptr)
        {
            head = newNode;
            tail = newNode;
        }
        else
        {
            tail->next = newNode;
            tail = newNode;
        }
    }

    return head;
}

// Imprime uma lista encadeada
void imprimirLista(ListNode *head)
{
    cout << "[";
    while (head != nullptr)
    {
        cout << head->val;
        if (head->next)
            cout << ",";
        head = head->next;
    }
    cout << "]" << endl;
}

int main()
{
    // Listas de exemplo
    vector<int> n1 = {9, 9, 9, 9, 9, 9, 9};
    vector<int> n2 = {9, 9, 9, 9};

    ListNode *l1 = createList(n1);
    ListNode *l2 = createList(n2);

    cout << "Lista 1: ";
    imprimirLista(l1);
    cout << "Lista 2: ";
    imprimirLista(l2);
    cout << endl;

    // Nó auxiliar dummy para construir a lista de resultado
    ListNode *dummy = new ListNode(0);
    ListNode *current = dummy;
    int parser = 0; // carry

    // Loop de soma
    while (l1 != nullptr || l2 != nullptr || parser != 0)
    {
        int x = (l1 != nullptr) ? l1->val : 0;
        int y = (l2 != nullptr) ? l2->val : 0;
        int sum = x + y + parser;

        current->next = new ListNode(sum % 10);
        parser = sum / 10;

        current = current->next;

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

    // Lista final de soma
    ListNode *answer = dummy->next;
    cout << "Resultado: ";
    imprimirLista(answer);

    return 0;
}