#include

class Node { public: int data; Node* next;

Node(int val) : data(val), next(nullptr) {}

};

class SinglyLinkedList { private: Node* head;

public: SinglyLinkedList() : head(nullptr) {}

void append(int val) {
    Node* newNode = new Node(val);
    if (!head) {
        head = newNode;
        return;
    }
    Node* temp = head;
    while (temp->next) temp = temp->next;
    temp->next = newNode;
}

void printList() {
    Node* temp = head;
    while (temp) {
        std::cout << temp->data << " -> ";
        temp = temp->next;
    }
    std::cout << "NULL" << std::endl;
}

void reverseLinkedList() {
    Node* prev = nullptr;
    Node* current = head;
    Node* next = nullptr;

    while (current != nullptr) {
        next = current->next;
        current->next = prev;
        prev = current;
        current = next;
    }

    head = prev;
}

};

int main() { SinglyLinkedList list; list.append(1); list.append(2); list.append(3); list.printList();

list.reverseLinkedList();
list.printList();

return 0;

}