HomeworkOOP1

import java.util.Scanner;

public class Program {

    public static int reverseNumber(int num) {
        String str = "";
        while (num != 0) {
            str += num % 10;
            num /= 10;
        }
        return Integer.parseInt(str);
    }

    public static double average(int[] arr) {
        double sum = 0;
        for (int i = 0; i < arr.length; i++) {
            sum += arr[i];
        }
        return sum / arr.length;
    }

    public static double findX(int a, int b) {
        double x = (double) -b / a;
        return x;
    }

    public static int reverseNum2(int num) {
        StringBuilder sb = new StringBuilder();
        sb.append(num);
        sb.reverse();
        return Integer.parseInt(sb.toString());
    }

    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
        while (true) {
            System.out.println("1. Reverse number");
            System.out.println("2. Find average");
            System.out.println("3. Find x");
            System.out.println("4. Exit");
            char menu = scan.nextLine().charAt(0);
            if (menu == '1') {
                System.out.print("Enter your number: ");
                int num = Integer.parseInt(scan.nextLine());
                if (num < 0) {
                    System.out.println("Negative number!");
                } else {
                    System.out.println("Reversed: " + reverseNumber(num));
                }
            } else if (menu == '2') {
                System.out.print("Enter your numbers: ");
                String[] nums = scan.nextLine().split(" ");
                if (nums.length == 0) {
                    System.out.println("Empty row!");
                } else {
                    int[] arr = new int[nums.length];
                    for (int i = 0; i < nums.length; i++) {
                        arr[i] = Integer.parseInt(nums[i]);
                    }
                    System.out.printf("Average: %.2f\n", average(arr));
                }
            } else if (menu == '3') {
                System.out.print("a = ");
                int a = Integer.parseInt(scan.nextLine());
                System.out.print("b = ");
                int b = Integer.parseInt(scan.nextLine());
                if (a == 0) {
                    System.out.println("No real roots!");
                } else {
                    System.out.printf("x = %.2f\n", findX(a, b));
                }
            } else {
                break;
            }
        }
    }
}