Java Programs - Solved 2020 ICSE Computer Science Paper

import java.util.Scanner;
class Menu{
    public static void main(String[] args){
        Scanner in = new Scanner(System.in);
        System.out.println("1. a^2 + 2ab");
        System.out.println("2. Pattern");
        System.out.print("Enter your choice: ");
        int choice = Integer.parseInt(in.nextLine());
        switch(choice){
        case 1:
            double a = 1.0;
            final double b = 3.0;
            double c;
            while(a <= 20.0){
                c = a * a + 2 * a * b;
                System.out.println("c = " + c);
                a += 2.0;
            }
            break;
        case 2:
            for(char i = 'A'; i <= 'E'; i++){
                for(char j = 'A'; j <= i; j++)
                    System.out.print(j);
                System.out.println();
            }
            break;
        default:
            System.out.println("Invalid choice!");
        }
    }
}