Add 1 to a Linked List Number

// User function template for C++

/*

struct Node
{
    int data;
    struct Node* next;

    Node(int x){
        data = x;
        next = NULL;
    }
};

*/

class Solution {
private:
    Node* reverse(Node* head) {
        Node* prev = nullptr;
        Node* current = head;
        Node* next = nullptr;
        while (current != nullptr) {
            next = current->next;
            current->next = prev;
            prev = current;
            current = next;
        }
        return prev;
    }

public:
    Node* addOne(Node* head) {
        if (head == nullptr) return new Node(1);
        
        // Step 1: Reverse the linked list
        head = reverse(head);
        
        // Step 2: Add 1 to the number
        Node* current = head;
        int carry = 1;
        
        while (current != nullptr && carry > 0) {
            int sum = current->data + carry;
            current->data = sum % 10;
            carry = sum / 10;
            
            if (carry > 0 && current->next == nullptr) {
                current->next = new Node(0);
            }
            
            current = current->next;
        }
        
        // Step 3: Reverse the list back
        return reverse(head);
    }
};