/*
 * Introduction to Programming, Autumn 2007, Exercise 3 (17.-21.9.)
 * Example solution
 * Task 10
 *
 * Make an interactive program Triangle that asks the width of the triengle and prints
 * it by using the characters "*". For example, if the width is 7, the program prints:

          *
         **
        ***
       ****
      *****
     ******
    *******

 * You may assume that the input really is of right type, integer in this case, as
 * you may do in all of the exercises, if not otherwise stated. Anyhow the value of
 * the integer should be checked, and error message printed, if the number has
 * invalid value. In that case a new number must be asked. 
 * 
 * Tuomas Blom, 15.9.2007
 */

import java.util.Scanner;

public class Triangle {
	private static Scanner reader = new Scanner(System.in);
	public static void main(String[] args) {
		int width;

		System.out.println("Welcome to Triangle!");
		System.out.println("This program prints a triangle on the screen.");

		System.out.println("Please enter the width of the triangle (1-30) >");
		width = reader.nextInt();
		while (width < 1 || width > 30) { // Keep asking until a proper value is entered
			// Display a message of what went wrong:
			if (width < 1) {
				System.out.println("I'm afraid I can't draw a triangle that small.");
			}
			else {
				System.out.println("I can't draw a triangle that big - I'm only a computer!");
			}
			System.out.println("Please enter a width between 1 and 30 >");
			width = reader.nextInt();
		}
		
		// Print the triangle:
		
		// Traverse the lines (triangle is as tall as it is wide)
		for (int line = 1; line <= width; line++) {
			// Print the empty characters
			int spaces = width-line;
			for (int i = 0; i < spaces; i++) {
				System.out.print(" "); // Note: print, not println!
			}
			// Print the asterisks of the current line
			for (int i = 0; i < line; i++) {
				System.out.print("*");
			}
			// End line:
			System.out.println();
		}
		
		System.out.println("\nThere you go! Pretty, huh?");
	}
}



/*
 * Introduction to Programming, Autumn 2007, Exercise 3 (17.-21.9.)
 * Example solution
 * Task 11
 * 
 * A year is a leap year, if it is divisible by 4, but not by 100. However, years
 * divisible by 400 are leap years. Anyhow, year 4000 is not a leap year. Make
 * an interactive program that prints all leap years within a user-defined range
 * of years. The user is allowed to give the endpoints of the range in any order.
 * The order of printing the years is decided by the order of the input years.
 *
 * Tuomas Blom, 15.9.2007
 */

import java.util.Scanner;

public class LeapYears {
	private static Scanner reader = new Scanner(System.in);
	
	public static void main(String[] args) {
		LeapYears ly;
		
		int yearStart;
		int yearEnd;

		// Ask the user to input the years (all integer values accepted)
		System.out.println("Enter a year >");
		yearStart = reader.nextInt();
		System.out.println("Enter another year >");
		yearEnd = reader.nextInt();
		
		System.out.println("Leap years between " + yearStart + " and " + yearEnd + " are:");
		
		// If start is earlier (or same) than end, print years in ascending order
		if (yearStart <= yearEnd) {
			for (int year = yearStart; year <= yearEnd; year++) {
				if (year % 4 == 0 && ((year % 100 != 0) || (year % 400 == 0)) && year != 40000) {
					System.out.println(year);
				}
			}
		}
		// Otherwise print years in descending order
		else {
			for (int year = yearStart; year >= yearEnd; year--) {
				if (year % 4 == 0 && ((year % 100 != 0) || (year % 400 == 0)) && year != 40000) {
					System.out.println(year);
				}
			}
		}
	}
	
	/*
	 * Advanced, but good to note:
	 * Checking leap years with such an if statement is a bit clumsy. It would be better
	 * to use a more readable and reusable method instead. Something like this:
	 */
	public static boolean isLeapYear(int year) {
		if (year % 4 == 0 && ((year % 100 != 0) || (year % 400 == 0)) && year != 40000) {
			return true; // yes, it's a leap year!
		}
		return false; // just a regular year
	}
}


/*
 * Introduction to Programming, Autumn 2007, Exercise 3 (17.-21.9.)
 * Example solution
 * Task 12
 * 
 * Make a program that first reads two integers, lowerLimit and upperLimit.
 * Then the program reads more input numbers, and writes "Hit!", when the
 * input number is in the range lowerLimit--upperLimit. Otherwise it prints
 * "Miss!" Number zero ends the program.
 *
 * Tuomas Blom, 15.9.2007
 */

import java.util.Scanner;

public class HitOrMiss {
	private static Scanner reader = new Scanner(System.in);
	
	public static void main(String[] args) {
		int lowerLimit, upperLimit;

		// Ask user for limit values
		System.out.println("Enter lower limit >");
		lowerLimit = reader.nextInt();
		System.out.println("Enter upper limit >");
		upperLimit = reader.nextInt();
		
		// Let's make sure lowerLimit actually is lower than (or at least equal to) upper limit
		if (lowerLimit > upperLimit) {
			int temp = lowerLimit;
			lowerLimit = upperLimit;
			upperLimit = temp;
		}
		
		// Ask for numbers and print the results
		int number;
		do {
			System.out.println("Enter a number (0 quits) >");
			number = reader.nextInt();
			if (number >= lowerLimit && number <= upperLimit) {
				System.out.println("Hit!");
			}
			else {
				System.out.println("Miss!");
			}
		} while (number != 0);
		
		System.out.println("Bye!");
	}
}


/*
 * Introduction to Programming, Autumn 2007, Exercise 3 (17.-21.9.)
 * Example solution
 * Task 13
 * 
 * Program the following computer game: First the program generates a random
 * integer: 0, 1, 2, ..., 9. Then the user inputs three guesses of that number.
 *
 * At the end the program informs the result:
 *  - If the first number the user gave is the same as the one generated by the
 *    program, the user wins 400 virtua euros.
 *  - If the second number the user gave is the same as the one generated by the
 *    program, the user wins 200 virtua euros.
 *  - If the third number the user gave is the same as the one generated by the
 *    program, the user wins 100 virtua euros.
 *  - If none of the numbers the user gave is the same as the one generated by
 *    the program, the user loses 100 virtua euros. 
 *
 * The user is allowed to guess also the same number 2 or 3 times; then both
 * the risk to lose and the size of the win increase.
 *
 * You can get a random number between 0 and 9 as follows:
 *
 *   int randomnunmber = (int)(10*Math.random());
 *   (Just use this expression, you don't have to understand it yet.)
 *   
 * In this critical gaming program you must also take care of errors, and ask
 * new numbers until the program gets valid input. The input can be wrong in
 * two different ways:
 *
 * 1. The input is not integer, perhaps not even numerical.
 * 2. The input is integer, but the value is not acceptable.
 * 
 * In case of errors the program must ask for new input.
 * 
 * Tuomas Blom, 15.9.2007
 */

import java.util.Scanner;

public class GuessingGame {
	private static Scanner reader = new Scanner(System.in);
	
	public static void main(String[] args) {
		
		System.out.println("** Welcome to Guessing Game **");
		System.out.println("Play and win virtual money!");
		
		// Create the random integer
		int randomNumber = (int)(10*Math.random());
		int firstGuess, secondGuess, thirdGuess;
		
		System.out.println("I've selected a number between 0 and 9. You have three attempts to guess what it is!");
		
		/* ** Guess #1: ** */
		firstGuess = -1; // Initialize guess to an unacceptable value
		System.out.println("Enter your first guess >");
				
		do { // Keep asking until user enters an integer between 0 and 9
			if (reader.hasNextInt()) {
				// An integer was entered, let's read it:
				firstGuess = reader.nextInt();
				if (firstGuess < 0 || firstGuess > 9) {
					// It was too small or large, print an error:
					System.out.println("My random number is between 0 and 9, please guess again >");
				}
			}
			else { // User entered something that wasn't an integer
				System.out.println("Please enter an integer between 0 and 9 >");
				reader.next(); // Discard the unsuitable input
			}
		} while (firstGuess < 0 || firstGuess > 9);
		
		// Guess #2:
		secondGuess = -1;
		System.out.println("Enter your second guess >");
		
		do {
			if (reader.hasNextInt()) {
				secondGuess = reader.nextInt();
				if (secondGuess < 0 || secondGuess > 9) {
					System.out.println("My random number is between 0 and 9, please guess again >");
				}
			}
			else { // not an integer
				System.out.println("Please enter an integer between 0 and 9 >");
				reader.next(); // discard
			}
		} while (secondGuess < 0 || secondGuess > 9);
		
		// Guess #3:
		thirdGuess = -1;
		System.out.println("Enter your third and final guess >");
		
		do {
			if (reader.hasNextInt()) {
				thirdGuess = reader.nextInt();
				if (thirdGuess < 0 && thirdGuess > 9) {
					System.out.println("My random number is between 0 and 9, please guess again >");
				}
			}
			else {
				System.out.println("Please enter an integer between 0 and 9 >");
				reader.next(); // discard
			}
		} while (thirdGuess < 0 || thirdGuess > 9);
		
		// Note how repetitive all that guessing code was. We really could have used a method
		// for reading a number between 0 and 9... Why don't you write one, just for fun! :-)
		
		// Okay, we should have three proper guesses now, let's calculate the score:
		int winnings = 0;
		if (firstGuess == randomNumber) {
			winnings += 400; 
		}
		if (secondGuess == randomNumber) {
			winnings += 200;
		}
		if (thirdGuess == randomNumber) {
			winnings += 100;
		}
		// If winnings is still 0, all of the guesses were wrong and the user loses 100 euros
		if (winnings == 0) {
			winnings -= 100;
		}
		
		// Now let's reveal the result:
		
		System.out.println("Your guesses were " + firstGuess + ", " + secondGuess + " and " + thirdGuess + ".");
		System.out.println("My random number was " + randomNumber + ".");
		if (winnings > 0) {
			System.out.println("That means you've won " + winnings + " virtual euros! Congratulations!");
		}
		else {
			System.out.println("Unlucky, you didn't guess my number. You owe me 100 virtual euros.");
		}
	}
}



/*
 * Introduction to Programming, Autumn 2007, Exercise 3 (17.-21.9.)
 * Example solution
 * Task 14
 * 
 * Program the following methods:
 * a) Reads one line of input and prints that input twice on the same line
 * b) Reads one input line and returns a String that is the input catenated with itself.
 * c) Prints the number given as parameter multiplied by the multiplier given as parameter.
 * d) Returns the number given as parameter multiplied by the multiplier given as parameter.
 * e) Returns a value that is the minimum of the two parameters.
 * f) Returns the value true if the first parameter is greater than the second, and returns false otherwise.
 * (This kind of methods are called class methods  or "static methods". This
 * particular way of using the class methods could be characterised as
 * programmins "main method's little helpers". This way way of using methods
 * is very traditional, but still commonly used. Other ways of using methods
 * will be seen soon...)
 *
 * Tuomas Blom, 15.9.2007
 */

import java.util.Scanner;

public class HelperMethods {
	private static Scanner reader = new Scanner(System.in);
	
	// Reads one line of input and prints that input twice on the same line
	private static void writeInputLineTwice() {
		System.out.println("Enter a line of input >");
		String line = reader.nextLine();
		System.out.println(line + line);
	}

	// Reads one input line and returns a String that is the input catenated with itself.
	private static String inputAsDouble() {
		System.out.println("Enter a line of input >");
		String line = reader.nextLine();
		return (line + line);
	}

	// Prints the number given as parameter multiplied by the multiplier given as parameter. 
	private static void printNumberMultiplied(int number, int multiplier) {
		System.out.println(number * multiplier);
	}

	// Returns the number given as parameter multiplied by the multiplier given as parameter.
	private static int multiply(int number, int multiplier) {
		return number * multiplier;
	}

	// Returns a value that is the minimum of the two parameters.
	private static double minimum(double first, double second) {
		if (first <= second) {
			return first;
		}
		else { // This else isn't necessary. See next method for explanation 
			return second;
		}
	}

	// Returns the value true if the first parameter is greater than the second, and returns false otherwise.
	private static boolean isGreater(int first, int second) {
		if (first > second) {
			return true;
		}
		// If first was greater, the execution of this method has already ended,
		// so we can just return false:
		return false;
	}
	
	/*
	 * Let's test those methods here
	 */
	public static void main(String[] args) {
		int a = 4, b = 8;
		double p = 3.14, q = 1.88;
		
		String resultString;
		int resultInt;
		double resultDouble;
		boolean resultBoolean;
		
		System.out.println("About to call method 'void writeInputLineTwice()' -->");
		writeInputLineTwice();
		System.out.println("<-- method finished.");

		System.out.println();
		
		System.out.println("About to call method 'String inputAsDouble()' -->");
		resultString = inputAsDouble();
		System.out.println("<-- method finished.");
		System.out.println("It returned '" + resultString + "'.");
		
		System.out.println();
		
		System.out.println("About to call method 'void printNumberMultiplied(" + a + ", " + b + ")' -->");
		printNumberMultiplied(a, b);
		System.out.println("<-- method finished.");
		
		System.out.println();
		
		System.out.println("About to call method 'int multiply(" + a + ", " + b + ")' -->");
		resultInt = multiply(a, b);
		System.out.println("<-- method finished.");
		System.out.println("It returned '" + resultInt + "'.");
		
		System.out.println();
		
		System.out.println("About to call method 'double minimum(" + p + ", " + q + ")'-->");
		resultDouble = minimum(p, q);
		System.out.println("<-- method finished.");
		System.out.println("It returned '" + resultDouble + "'.");
		
		System.out.println();
		
		System.out.println("About to call method 'boolean isGreater(" + a + ", " + b + ")' -->");
		resultBoolean = isGreater(a, b);
		System.out.println("<-- method finished.");
		System.out.println("It returned '" + resultBoolean + "'.");
		
	}
}