“head.h”

#include<iostream>
using namespace std;

class NODE
{
public:
	NODE();
	int num;
	NODE *next;
};

NODE::NODE()
{
	num = 0;
	next = NULL;
}

class DATA
{
public:
	DATA();
	void Constructor();
	void Print();
	void Process();
private:
	NODE *head1, *head2, *head3, *p, *pr, *keep;
	int first;
};

DATA::DATA()
{
	head1 = head2 = head3 = p = pr = keep = NULL;
	first = 1;
}

void DATA::Constructor()
{
	if (first <= 3)
	{
		cout << "Constructor " << first << " called !" << endl;
	}
	else
		return;
	cout << "How Many Numbers Do You Want To Enter ?" << endl << endl;
	int nnum, input;
	cin >> nnum;
	if (nnum != 0)
	{
		p = new NODE;
		cin >> input;
		p->num = input;
		switch (first)
		{
		case 1:
			head1 = p;
			break;
		case 2:
			head2 = p;
			break;
		case 3:
			head3 = p;
			break;
		}
		nnum--;
	}
	while (nnum--)
	{
		p->next = new NODE;
		p = p->next;
		cin >> input;
		p->num = input;
	}
	p->next = NULL;
	first++;
}

void DATA::Print()
{
	cout << "Print called !" << endl << endl;
	p = head1;
	if (p == NULL)
		cout << "No Data !" << endl;
	while (p != NULL)
	{
		cout << p->num << endl;
		p = p->next;
	}
	cout << endl;
}

void DATA::Process()
{
	cout << "Processor called !" << endl << endl;
	pr = p = head1;
	while (head2 != NULL && head3 != NULL)
	{
		if (head2->num < p->num)
		{
			keep = head2;
			head2 = head2->next;
			delete keep;
		}
		if (head3->num < p->num)
		{
			keep = head3;
			head3 = head3->next;
			delete keep;
		}
		if (head2 == NULL || head3 == NULL)
			return;
		if (head2->num == p->num && head3->num == p->num)
		{
			if (p == head1)
			{
				head1 = head1->next;
				delete p;
				p = pr = head1;
			}
			else
			{
				pr->next = p->next;
				delete p;
				p = pr->next;
			}
			if (p == NULL)
				return;
		}
		if ((head2->num >= p->num && head3->num > p->num)
				|| (head2->num > p->num && head3->num >= p->num))
		{
			pr = p;
			p = p->next;
			if (p == NULL)
				return;
		}
	}
}

“main.cpp”

#include<iostream>
#include"head.h"
using namespace std;
 
int main()
{
	DATA data;
	data.Constructor();
	data.Constructor();
	data.Constructor();
	data.Process();
	data.Print();
	system("pause");
}