You have two numbers represented by a linked list, where each node contains a sin- gle digit The digits are stored in reverse order, such that the 1’s digit is at the head of the list Write a function that adds the two numbers and returns the sum as

Sum.cpp

#include <iostream>
#include <boost/smart_ptr.hpp>

typedef struct node{
	int value;
	boost::shared_ptr<struct node> next;
}NODE;

boost::shared_ptr<NODE> Null = boost::shared_ptr<NODE>();

void printList(boost::shared_ptr<NODE> list){
	if( list == Null )
		return;

	boost::shared_ptr<NODE> curr = list->next;
	while( curr != Null ){
		std::cout << curr->value << " -> ";
		curr = curr->next;
	}
	std::cout << "NULL" << std::endl;
}

boost::shared_ptr<NODE> constructList(const int operand){
	boost::shared_ptr<NODE> head = boost::shared_ptr<NODE>(new NODE);
	boost::shared_ptr<NODE> curr = head;
	int temp = operand;

	while( temp >= 0 )
	{
		curr->next = boost::shared_ptr<NODE>(new NODE);
		curr = curr->next;

		curr->value = temp%10;
		curr->next = Null;

		temp = temp/10;

		if( temp == 0 )
			break;
	}

	return head;
}

boost::shared_ptr<NODE> sum(boost::shared_ptr<NODE> operand1, boost::shared_ptr<NODE> operand2)
{
	boost::shared_ptr<NODE> result = boost::shared_ptr<NODE>(new NODE);
	boost::shared_ptr<NODE> currResult = result;
	boost::shared_ptr<NODE> currOp1 = operand1->next;
	boost::shared_ptr<NODE> currOp2 = operand2->next;
	int carry = 0;
	int sum = 0;	

	while(currOp1 != Null || currOp2 != Null){
		sum = 0;

		if( currOp1 != Null ){
			sum += currOp1->value;
			currOp1 = currOp1->next;
		}
		if( currOp2 != Null ){
			sum += currOp2->value;
			currOp2 = currOp2->next;
		}
		sum += carry;

		currResult->next = boost::shared_ptr<NODE>(new NODE);
		currResult = currResult->next;
		currResult->next = Null;

		if( sum >= 10 ){
			carry = 1;
			sum = sum%10;
		}else{
			carry = 0;
		}

		currResult->value = sum;
	}

	return result;
}

int main(int argc, char *argv[])
{
	int operand1, operand2;

	std::cin >> operand1 >> operand2;

	boost::shared_ptr<NODE> operandList1 = constructList(operand1); 
	std::cout << "Operand 1 is:" << std::endl;
	printList(operandList1);
	boost::shared_ptr<NODE> operandList2 = constructList(operand2); 
	std::cout << "Operand 2 is:" << std::endl;
	printList(operandList2);

	std::cout << "Result is:" << std::endl;
	printList(sum(operandList1, operandList2));
	return 0;		
}