5.binary_code

//writing the void get_bin(int n) function is a good trick n logic. SEE IT.

//Take count of the no of digits in the get_binary function itself.
//and , compare those in main and add the reqd zero's to get the reqd result.
//set sum and carry to zero while performing addn
//use a^b^c for sum
//use ab +bc + ac for carry
//Take care of how we do the 1s and 2s complement.


#include <iostream>
using namespace std;
class node
{
	bool digit;
	node* next;
	node* prev;
public:
	friend class ll;
};

class ll
{
public:
	node* head;
	node* tail;
	bool sum;
	bool carry;
	ll()
	{
		head = tail = NULL;
	}
	void get_bin(int n);
	void insert_front(bool b);
	void insert_back(bool b);
	void display();
	void ones(node* start);
	void twos(node* end);
	void add(node* end1,node* end2);
	int counter();
};

void ll::insert_front(bool b)
{
	node* nn = new node;
	nn->digit = b;
	nn->next = NULL;
	nn->prev = NULL;

	if (head == NULL && tail == NULL)//empty
	{
		head = tail = nn;
	}
	else//not empty
	{
		nn->next = head;
		head->prev = nn;
		head = nn;
	}
}

void ll::insert_back(bool b)
{
	node* nn = new node;
	nn->digit = b;
	nn->next = NULL;
	nn->prev = NULL;

	if (head == NULL && tail == NULL)//empty
	{
		head = tail = nn;
	}
	else//not empty
	{
		tail->next = nn;
		nn->prev = tail;
		tail = nn;
	}
}


void ll::get_bin(int n)
{
	while (n != 1)
	{
		if (n % 2 == 0)
		{
			insert_front(0);
		}
		else
		{
			insert_front(1);
		}
		n = n / 2;
	}
	insert_front(1);
}

void ll::ones(node* start)
{
	while (start != NULL)
	{
		if (start->digit == 1)
		{
			insert_back(0);
		}
		else
		{
			insert_back(1);
		}

		start = start->next;
	}
}

void ll::twos(node* end)
{
	if (end->digit == 0)
	{
		insert_front(1);
		carry = 0;
	}
	else
	{
		insert_front(0);
		carry = 1;
	}

	end = end->prev;

	while (end != NULL)
	{
		if (carry == 0)
		{
			insert_front(end->digit);
		}
		else
		{
			if (end->digit == 0)
			{
				insert_front(1);
				carry = 0;
			}
			else
			{
				insert_front(0);
				carry = 1;
			}
		}

		end = end->prev;
	}
	
	if (carry==1)
	{
		insert_front(1);
	}
}

void ll::add(node* end1, node* end2)
{
	sum = 0;
	carry = 0;

	while (end1 != NULL)
	{
		sum = (end1->digit ^ end2->digit ^ carry);
		carry = (end1->digit & end2->digit) | (end2->digit & carry) | (end1->digit & carry);
		insert_front(sum);

		end1 = end1->prev;
		end2 = end2->prev;
	}

	if (carry==1)
	{
		insert_front(1);
	}
}

void ll::display()
{
	node* start = head;
	cout << "---Display---" << endl;
	while (start != NULL)
	{
		cout << start->digit << " " ;
		start = start->next;
	}
	cout << endl;
}

int ll::counter()
{
	int count = 0;
	node* start = head;
	while (start != NULL)
	{
		count++;
		start = start->next;
	}
	return count;
}


int main()
{
	int n,n2;
	cout << "Enter the decimal number" << endl;
	cin >> n;

	ll a;

	a.get_bin(n);
	a.display();

	ll b;

	cout << "\n\t1's Complement" << endl;
	b.ones(a.head);
	b.display();

	ll c;

	cout << "\n\t2's Complement" << endl;
	c.twos(b.tail);
	c.display();

	ll a2;

	cout << "Enter another decimal number" << endl;
	cin >> n2;
	a2.get_bin(n2);
	a2.display();

	cout << "\n\tAddition" << endl;

	ll e;

	int c1 = a.counter();
	int c2 = a2.counter();

	if (c1 == c2)
	{
		e.add(a.tail, a2.tail);
	}
	else if (c1 > c2)
	{
		for (int i = 0; i < c1 - c2; i++)
		{
			a2.insert_front(0);
		}
		e.add(a.tail, a2.tail);
	}

	else
	{
		for (int i = 0; i < c2 - c1; i++)
		{
			a.insert_front(0);
		}
		e.add(a.tail, a2.tail);
	}

	e.display();

	return 0;
}