Question

I only need help with the constructors and add method. Thanks!

Background Arbitrary length integers are integers that have no size restriction. Recall that the int type has a range of -2,147,483,648 to 2,147,483,647. The long type runs from -263 to 263 - 1. Sometimes these numbers are not large enough. One example application that may need larger numbers is public-key cryptography where very large integers are used to make decryption hard. A large integer may be represented as a linked list by storing each digit in a node and linking the digits together in the correct sequence. For example, the number 45341 would be represented by the list [4, 5, 3, 4, 1 Details Implement a class called LinkedLargeInteger. LinkedLargeIntegers are to be immutable. LinkedL,argeInteger is to have the following methods. (Note: Java has a BigInteger class for this, implemented using an array rather than a linked list. You are not to use it You are not to use any of the Java Collections Framework for this assignment. You are to implement your linked list directly Begin by writing an interface called LargeInteger that specifies these public methods LinkedLargeInteger will then implement the LargeInteger interface. You need only handle non-negative numbers for this assignment 1. constructor - takes a String representing the large number and creates the linked represen tation. 2. constructor - takes an int representing the large number and creates the linked representa- tion 3. constructor - takes a long representing the large number and creates the linked representa- tion 4. add - takes a LinkedL,argeInteger; returns the LinkedLargeInteger sum of this and the argument 5. subtract - takes a LinkedLargeInteger; returns the LinkedLargeInteger difference of this and the argument 6. multiply - takes a LinkedLargeInteger; returns the LinkedLargeInteger product of this and the argument 7. compareTo - takes an Object; returns 1 if this is greater than the argument, 0 if they are equal, and -1 if this is less than the argument. Recall that this means LargeInteger will extend the Comparable interface 8. equals 9. hashCode 10. toString You might find it helpful to create two LinkedLargeInteger constants ZERO and ONE. Write a main method to test your code. Test your code

Answer 1

Please find the code below:

LinkedLargeInteger.java

package classes13;

public class LinkedLargeInteger{

public class ListNode {

public int data;

public ListNode next;

public ListNode(int data) {

this.data = data;

this.next = null;

}

public ListNode(int data, ListNode next) {

this.data = data;

this.next = next;

}

}

private ListNode front; // refers to first node in list (null if empty)

public String thisString;

private int index = 0;

public LinkedLargeInteger(String s) {

thisString = s;

front = null; // null front means empty

int l1 = s.length();   

for (int i = l1 - 1; i >= 0; i--)

add(s.charAt(i) - '0');

}

public void add(int value) {

if (index == 0) {

// insert at the front

front = new ListNode(value, front);

} else {

// insert in middle/end; walk to node before the one to insert

ListNode current = goTo(index - 1);

ListNode newNode = new ListNode(value, current.next);

current.next = newNode;

}

index++;

}

public int get(int index) {

ListNode current = goTo(index);

return current.data;

}

public int size() {

int count = 0;

ListNode current = front;

while (current != null) {

current = current.next;

count++;

}

return count;

}

private ListNode goTo(int index) {

ListNode current = front;

for (int i = 0; i < index; i++) {

current = current.next;

}

return current;

}

LinkedLargeInteger add(LinkedLargeInteger num2){

int l1 = thisString.length();

LinkedLargeInteger ans = new LinkedLargeInteger("");

int l2 = num2.thisString.length();

int len = l1 > l2 ? l1 : l2;

int carry = 0;

for (int i = 0; i < len; i++)

{

int d1 = 0, d2 = 0;   

try {

d1 = get(i);

}

catch(Exception e){}   

try {

d2 = num2.get(i);

}

catch(Exception e){}   

int x = d1 + d2 + carry;

ans.add(x % 10);

carry = x / 10;

}

/* Adding carry */

while (carry != 0)

{

ans.add(carry % 10);

carry /= 10;

}

return ans;

}

}

LinkedLargeIntegerTester.java

package classes13;

/*

* Java Program to add two large numbers using Linked List

*/

import java.util.Scanner;

public class LinkedLargeIntegerTester

{

public static void main(String[] args)

{   

Scanner scan = new Scanner(System.in);

/* Create Linked Lists */

/* Accept numbers */

System.out.println("Adding Large Numbers Using Linked Lists Test\n");

System.out.println("Enter number 1");

String s1 = scan.next();

System.out.println("Enter number 2");

String s2 = scan.next();

/* Store digits in lists */

LinkedLargeInteger num1 = new LinkedLargeInteger(s1);

LinkedLargeInteger num2 = new LinkedLargeInteger(s2);

LinkedLargeInteger ans = num1.add(num2);

System.out.print("\nSum = ");

for (int i = ans.size() - 1; i >= 0; i--)

System.out.print(ans.get(i));

System.out.println();   

}

}

output: