Please do changes in this code. This is a simple Nodepad code in C++ using multilevel linked list. If you can do please add some additional functionalities in it.

#include

#include

#include

#include

using namespace std;

class Node {

public:

char data;

Node* left = NULL;

Node* right = NULL;

Node* up = NULL;

Node* down = NULL;

};

Node* head, * tail, * upper_head, * lower_head, root;

Node** arr = new Node * [100];

int row = 0;

void reset() {

head = NULL;

tail = NULL;

}

Node* newNode(char val) {

Node* node = new Node();

node->data = val;

if (head == NULL) {

head = node;

tail = node;

}

return node;

}

void verticle_link() {

upper_head = arr[row - 1];

lower_head = head;

}

void make_doubly_list(char res) {

Node* temp = newNode(res);

tail->right = temp;

temp->left = tail;

tail = temp;

if (row != 0) {

if (upper_head != NULL) {

temp->up = upper_head;

upper_head->down = temp;

upper_head = upper_head->right;

}

}

}

void make_arr() {

arr[row] = head;

reset();

row++;

}

class Note : public Node {

char res{};

string err = "\t oh no! invalid entry! ";

public:

void header();

void menu();

void enterText();

void save(char);

void read();

};

void Note::header() {

cout << "\t Note-pad /c++" << endl << endl;

}

void Note::menu() {

lmao: header();

cout << "1. Enter note" << endl;

cout << "2. Read Notes" << endl;

cout << "3. Exit program" << endl;

repeat: try {

cout << " Enter response: ";

cin >> res;

if (res == '1') {

enterText();

}

else if (res == '2') {

read();

}

else if (res == '3') {

exit(0);

}

else if (res == '4') {

cout << arr[0]->right->right->down->data;

}

else

throw err;

}

catch (string err) {

cout << err << endl;

goto repeat;

}

goto lmao;

}

void Note::enterText() {

system("CLS");

cout << "Enter 0 to stop" << endl;

cout << "Enter here: " << endl;

while (1) {

res = _getch();

if (res == '0')

break;

else if (res == ' ') {

cout << endl;

save(' ');

res = _getch();

cout << res;

make_arr();

verticle_link();

make_doubly_list(res);

save(res);

}

else {

cout << res;

make_doubly_list(res);

save(res);

}

}

}

void Note::save(char r) {

if (r != '0') {

ofstream note_write("notepad.txt", ios::app);

note_write << r;

}

}

void Note::read() {

string data;

ifstream note_read("notepad.txt");

while (getline(note_read, data)) {

cout << data << endl;

}

}

int main() {

Note notepad_1;

notepad_1.menu();

return 0;

}