// Helene Martin, CSE 142
// Demonstrates usage of the Random class.
// Simulates dice rolls (I got excited so I had to code it up.  Expected value!).

import java.util.*;

public class RandomDemo {
	public static final int SIMULATION_COUNT = 100000;

	public static void main(String[] args) {
		Random rand = new Random();
		
		// A random number between 1 and 47 inclusive?
		int num1 = rand.nextInt(47) + 1;
		/*
		Add 1 to shift the range by 1. Example: 
		rand.nextInt(3)	 	+1
		0 						-> 1
		1 						-> 2
		2 						-> 3
		*/

		// A random number between 23 and 30 inclusive?
		// Number of different choices: max - min + 1
		// to generate a number in the range [min, max]:
		//     rand.nextInt(number of choices) + min;
		int num2 = rand.nextInt(8) + 23;

		// A random even number between 4 and 12 inclusive?
		int num3 = (rand.nextInt(5) + 2) * 2;
		
		int triesUntil7 = diceRolls(rand);
		System.out.println("You got it in " + triesUntil7 + " times");	
		
		int totalTries = 0;
		int runs = 0;
		for (int i = 0; i < SIMULATION_COUNT; i++) {
			totalTries += diceRolls(rand);
			runs++;
		}	
		System.out.println("Average tries after " + SIMULATION_COUNT + " runs: " + (double)totalTries / runs); 
	}
	
	// Simulates rolling two dice until their sum is 7.
	// Returns the number of rolls that takes.
	public static int diceRolls(Random rand) {
		int times = 0;
		int sum = -1;
		while (sum != 7) { 
			int die1 = rand.nextInt(6) + 1;
			int die2 = rand.nextInt(6) + 1;
			times++;
			
			sum = die1 + die2;
			
			// commented out for 100,000 runs
			//System.out.println(die1 + " + " + die2 + " = " + sum);
		}
		return times;
	}
}