import java.text.DecimalFormat; // for formatting doubles
import uwcse.io.*;

/**
 * Practicing using loops
 */

public class Loops {

	/**
	 * Check that the sum of the cubes is the square of the sum
	 * <p>
	 * 
	 * i.e. (^ means exponentiation (not available in java)) <br>
	 * 1^3 + 2^3 + 3^3 + ... + n^3 = (1 + 2 + 3 + ... + n)^2 <br>
	 * Use a loop to allow the user to test the formula with several values of
	 * n. Exit the loop if n is not a positive integer.
	 */
	public void sum3vsSum2() {
		int n;
		Input input = new Input();
		System.out.println("Sum of the cubes / square of the sum");

		do { // Input n until n<=0
			n = input.readInt("Enter an integer (<=0 to quit): ");

			int sum = 0; // sum
			int sumCubes = 0; // sum of the cubes

			// Compute sum and sumCubes
			// use a for loop
			for (int i = 1; i <= n; i++) {
				sum += i;
				sumCubes += (int) (Math.pow(i, 3));
			}

			if (n > 0)
				System.out.println("Sum of the cubes: " + sumCubes
						+ "\nSquare of the sum: " + sum * sum);
		} while (n > 0);
	}

	/**
	 * Display shapes of stars
	 * <p>
	 * In a console window, display the following shapes using for loops
	 * 
	 * <pre>
	 * 
	 *  *         *
	 *  **       **
	 *  ***     ***
	 *  ****   ****
	 * 
	 * </pre>
	 * 
	 * Allow the user to select the number of lines. Repeat the process until
	 * the user inputs a non positive value for the number of lines.
	 */
	public void figuresOfStars() {
		int n;
		Input input = new Input();
		System.out.println("Display of stars");

		do {
			n = input.readInt("Enter the number of lines (<=0 to quit): ");
			for (int i = 1; i <= n; i++) {
				// print the line for the left triangle
				for (int j = 1; j <= i; j++)
					System.out.print("*");
				// gap between the two triangles
				for (int j = 1; j <= 2 * (n - i) + 2; j++)
					System.out.print(" ");
				// print the line for the right triangle
				for (int j = 1; j <= i; j++)
					System.out.print("*");
				// Go to the next line
				System.out.println();
			}
		} while (n > 0);
	}

	/**
	 * Sum the digits of a positive integer
	 * <p>
	 * Let the user enter an integer.<br>
	 * If the integer is positive, sum all of the digits of the integer. Repeat
	 * the process until you get a single digit answer:<br>
	 * for instance, 123456 gives 21 which gives 3<br>
	 * Repeat the process until the user inputs a non positive value for the
	 * integer.
	 */
	public void sumDigits() {
		int n;
		Input input = new Input();
		System.out.println("Sum the digits");

		int nSave;
		do {
			n = input.readInt("Enter an integer (<=0 to quit): ");
			int sum; // sum of the digits of n.
			nSave = n; // n will be modified. Save its initial value.
			do {
				sum = 0;
				while (n > 0) {
					sum += n % 10; // add to sum the rightmost digit of n
					n /= 10; // shift all of the digits by one to the right.
					// the rightmost digit is dropped.
				}
				n = sum;
			} while (n >= 10);
			if (sum > 0)
				System.out.println(nSave + " yields " + sum);
		} while (nSave > 0);
	}

	/**
	 * Rolling a die
	 * <p>
	 * Let the user enter an integer n. Roll a dice n times and display how many
	 * times each face comes out.<br>
	 * Repeat the process until the user enters a non positive value for n.
	 */
	public void rollADie() {
		int n;
		Input input = new Input();
		System.out.println("Roll a die");

		do {
			// To format the percentages
			DecimalFormat twoDigits = new DecimalFormat("0.00");
			n = input.readInt("Enter an integer (<=0 to quit): ");
			// Count the numbers of ones, twos, threes... that come out.
			int one = 0, two = 0, three = 0, four = 0, five = 0, six = 0;
			// Roll the die n times
			for (int i = 1; i <= n; i++) {
				switch ((int) (Math.random() * 6) + 1)
				// generate a random integer between 1 and 6
				// and count how many times each value comes out.
				{
				case 1:
					one++;
					break;
				case 2:
					two++;
					break;
				case 3:
					three++;
					break;
				case 4:
					four++;
					break;
				case 5:
					five++;
					break;
				case 6:
					six++;
					break;
				}
			}
			if (n > 0)
				System.out.println("Face 1: " + one + " or "
						+ twoDigits.format(100. * one / n) + "%\n" + "Face 2: "
						+ two + " or " + twoDigits.format(100. * two / n)
						+ "%\n" + "Face 3: " + three + " or "
						+ twoDigits.format(100. * three / n) + "%\n"
						+ "Face 4: " + four + " or "
						+ twoDigits.format(100. * four / n) + "%\n"
						+ "Face 5: " + five + " or "
						+ twoDigits.format(100. * five / n) + "%\n"
						+ "Face 6: " + six + " or "
						+ twoDigits.format(100. * six / n) + "%\n");
		} while (n > 0);
	}

	/**
	 * Starts the application
	 */
	public static void main(String[] args) {
		Loops lp = new Loops();
		lp.sum3vsSum2();
		lp.figuresOfStars();
		lp.sumDigits();
		lp.rollADie();
	}
}