how to solve this program

Question

#include <iostream>
using namespace std;

class base { protected: int a;
public: int b;

__________ //LINE 1

base(int x, int y): a(x), b(y) { }
~base() { }
void callme(int i, int j) { a = i; b = j; cout << a << b; }
};

class derived : public base { protected: int c;
public: int d;

__________ //LINE 2

derived(int x, int y): c(x), d(y) { a = b = 0; }
~derived() { }
void callme() { cout << endl << a << endl << b; }
};

class dderived :public derived { protected: int e;
public: int f;

__________ //LINE 3

dderived(int x, int y): e(x), f(y) { a = b = c = d = 0; }
~dderived() { }
void callme() { cout << endl << a << endl << b << endl << c << endl << d; }
};
class ddderived : protected dderived { private: int g, sum;
public: int h;
ddderived(int x, int y): g(x), h(y) {
a = 3 * g; b = 3 * h; c = 3 * a; d = 3 * b; e = 3 * c; f = 3 * d;
}
~ddderived() { }
void callme() { sum = a + b + b + c + d + e + f; cout << sum; }
};

int main() {
base b1; derived d1; dderived d2;
int q, r;
cin >> q >> r;

ddderived d3(q, r);
d3.callme();

return 0;
}

Answer 1

Sry post deleted
Answers
Line 1=base(){}
Line 2=derived(){}
Line 3=dderived(){}

Answer 2

Wow Esakki well done

Answer 3

sorry can't understand

Answer 4

Its ok Esakki

Answer 5

fill in the blanks with constructor

Answer 6

A perfect mindset!

Answer 7

#include <iostream>
using namespace std;

class base { protected: int a;
public: int b;

__________ //LINE 1

base(int x, int y): a(x), b(y) { }
~base() { }
void callme(int i, int j) { a = i; b = j; cout << a << b; }
};

class derived : public base { protected: int c;
public: int d;

__________ //LINE 2

derived(int x, int y): c(x), d(y) { a = b = 0; }
~derived() { }
void callme() { cout << endl << a << endl << b; }
};

class dderived :public derived { protected: int e;
public: int f;

__________ //LINE 3

dderived(int x, int y): e(x), f(y) { a = b = c = d = 0; }
~dderived() { }
void callme() { cout << endl << a << endl << b << endl << c << endl << d; }
};
class ddderived : protected dderived { private: int g, sum;
public: int h;
ddderived(int x, int y): g(x), h(y) {
a = 3 * g; b = 3 * h; c = 3 * a; d = 3 * b; e = 3 * c; f = 3 * d;
}
~ddderived() { }
void callme() { sum = a + b + b + c + d + e + f; cout << sum; }
};

int main() {
base b1; derived d1; dderived d2;
int q, r;
cin >> q >> r;

ddderived d3(q, r);
d3.callme();

return 0;
}