Question

Write a Java program called EqualSubsets that reads a text file, in.txt, that contains a list of positive and negative integers (duplicates are possible) separated by spaces and/or line breaks. Zero may be included. After reading the integers, the program saves them in a singly linked list in the same order in which they appear in the input file. Then, without changing the linked list, the program should print whether there exists two subsets of the list whose sums are the same and their lengths differ by at most 1. The lengths of a subset may not be empty. You must output YES if subsets exist that fit this criteria otherwise output NO.

Answer 1

import java.io.File;
import java.io.FileNotFoundException;
import java.util.Scanner;

class LinkedList {
    private Node head;

    static class Node {
        private int data;
        private Node next;

        public Node(int d) {
            data = d;
            next = null;
        }
    }

    public void append(int data) {
        Node n = new Node(data);
        if (head == null) {
            head = new Node(data);
        } else {
            n.next = null;
            Node last = head;
            while (last.next != null)
                last = last.next;
            last.next = n;
        }
    }

    public int sum(int index, int size) {
        Node current = head;
        int count = 0;
        int sum = 0;
        boolean found = false;
        while (current != null) {
            if (count == index) {
                found = true;
                break;
            }
            count++;
            current = current.next;
        }
        int i = 1;
        while (found && current != null && i <= size) {
            sum += current.data;
            i++;
            current = current.next;
        }
        return sum;
    }

    public void printList() {
        Node temp = head;
        while (temp != null) {
            System.out.print(temp.data + " ");
            temp = temp.next;
        }
        System.out.println();
    }

    public static void main(String[] args) throws FileNotFoundException {
        LinkedList list = new LinkedList();
        File file = new File("in.txt");
        Scanner sc = new Scanner(file);
        int count = 0;
        while (sc.hasNext()) {
            count++;
            list.append(Integer.parseInt(sc.next()));
        }
        System.out.println("\nCreated Linked list is: ");
        list.printList();
        if (count == 0) {
            return;
        }
        System.out.println("\n\n Subset exist? " + list.equalSubsets(count));
    }

    public boolean equalSubsets(int count) {
        for (int k = 2; k < (count - 1); k++) {
            for (int i = 0; i <= (count - k); i++) {
                int sum = sum(i, k);
                for (int j = 0; j <= (count - k); j++) {
                    if (i != j) {
                        if (sum == sum(j, k))
                            return true;
                        else if (sum == sum(j, k + 1))
                            return true;
                    }
                }
            }
        }
        return false;
    }
}