Answer - QUESTION1 : Pairs

scratch_4.java

import java.util.*;

class Pair {
    int x;
    int y;

    @Override
    public String toString() {
        return "{" +
                "x=" + x +
                ", y=" + y +
                '}';
    }
}

class Question1 {
    // Please try not to change anything in this method.
    public static void main(String[] args) {
        int[] numbers = new int[15];
        addRandomNumbers(numbers);
        System.out.println(Arrays.toString(numbers));
        System.out.println(findPairs(numbers, 10));
    }

    // Please try not to change anything in this method.
    public static void addRandomNumbers(int[] array) {
        for (int i = 0; i < array.length; i++) {
            array[i] = new Random().nextInt() % 10;
        }
    }

    // Try to complete this method.
    public static List<String> findPairs(int[] numbers, int desiredSum) {
        Arrays.sort(numbers);
        int a = 0;
        int b = numbers.length - 1;
        HashSet<Pair> pairHashSet = new HashSet<>();
        for(int i = 0; i < numbers.length;i++){
            if((numbers[a] + numbers[b] == desiredSum) && (a != b))
            {
                Pair p = new Pair();
                p.x = numbers[a];
                p.y = numbers[b];
                pairHashSet.add(p);
                a = a + 1;
                b = b - 1;
            }
            else if (numbers[a] + numbers[b] > desiredSum)
            {
                b = b - 1;
            }
            else
            {
                a = a + 1;
            }

        }
        System.out.println(pairHashSet);
        return null;
    }
}
//NAME : Aryan Dixit
//SECTION : G
//CLASS ROLL NUMBER : 35
//UNIVERSITY ROLL NUMBER : 191500156

• Use single-class imports instead of multiple-class imports!
• Please use ctrl+alt+shift+L to properly format your code in IntelliJ.
• Try to use IntelliJ code hints (look out for highlights in the code)! It will help simplify your code.
• Try to use modern Java language syntax in the code such as the var keyword for "Local Variable Type Inferencing".
• Try to write better names for variables.

Here is a formatted version of your code

import java.util.*;
import java.util.stream.Collectors;

// try to make this class generic!
class Pair {
    int firstNumber;
    int secondNumber;

    public Pair(int firstNumber, int secondNumber) {
        this.firstNumber = firstNumber;
        this.secondNumber = secondNumber;
    }

    @Override
    public String toString() {
        return "{" + firstNumber + ", " + secondNumber + "}";
    }
}

class Question1 {
    // Please try not to change anything in this method.
    public static void main(String[] args) {
        int[] numbers = new int[15];
        addRandomNumbers(numbers);
        System.out.println(Arrays.toString(numbers));
        System.out.println(findPairs(numbers, 10));
    }

    // Please try not to change anything in this method.
    public static void addRandomNumbers(int[] array) {
        for (int i = 0; i < array.length; i++) {
            array[i] = new Random().nextInt() % 10;
        }
    }

    // Try to complete this method.
    public static List<String> findPairs(int[] numbers, int desiredSum) {
        Arrays.sort(numbers);
        int leftIndex = 0;
        int rightIndex = numbers.length - 1;
        HashSet<Pair> pairHashSet = new HashSet<>();
        for (int i = 0; i < numbers.length && leftIndex != rightIndex; i++) {
            if ((numbers[leftIndex] + numbers[rightIndex] == desiredSum)) {
                Pair pair = new Pair(numbers[leftIndex], numbers[rightIndex]);
                pairHashSet.add(pair);
                leftIndex = leftIndex + 1;
                rightIndex = rightIndex - 1;
            } else if (numbers[leftIndex] + numbers[rightIndex] > desiredSum) {
                rightIndex = rightIndex - 1;
            } else {
                leftIndex = leftIndex + 1;
            }

        }
        // the method should return the list
        System.out.println(pairHashSet);
        return null;
    }
}