import java.util.Scanner;

public class MultiplicationTriangle {

    public MultiplicationTriangle() {
        int rowsEntered;

        System.out.println("Multiplication Triangle");
        printTriangle(4); // print one example

        do {
            Scanner input = new Scanner(System.in);
            System.out.print("Enter the number of rows you would like to print: ");
            rowsEntered = Integer.parseInt(input.nextLine());
            printTriangle(rowsEntered);
        } while (rowsEntered > 0);
        System.out.println("Thank you for using this program!");

    }

    private void printTriangle(int maxRows) {
        System.out.println("\nNumber of rows for this triangle: " + maxRows);
        for (int column = 1; column <= maxRows; column++) { // print header
            System.out.print(String.format("%4d", column));
        }
        System.out.println();

        for (int row = 1; row <= maxRows; row++) {
            for (int column = 1; column <= row; column++) {
                System.out.print(String.format("%4d", column * row));
            }
            System.out.println();
        }
    }

    public static void main(String[] args) {
        new MultiplicationTriangle();
    }
}