/**
 * This program calculates pi using the monte carlo method
 * 
 * Mark Monarch
 * 2/26/15
 */
import java.util.Scanner;

public class piCalculator
{
    public static void main()
    {
        // set up input
        Scanner in = new Scanner(System.in);
        
        // declare variables
        long    trials,
                inCircle = 0;
        double  x,
                y,
                piEstimate = 0;
        
        // asks user for number of trials. The more trials the more accurate
        System.out.print("Input number of trials: ");
        trials = in.nextLong();
        
        // run trials
        for (int i = 0; i < trials; i++)
        {
            System.out.println("step " + (i+1) + " of " + trials );
            for (int j = 0; j < 100000000; j++)
            {
                x = Math.random();
                y = Math.random();
                if (x*x+y*y <= 1)
                {
                    inCircle++;
                }
            }
            piEstimate += 4.0 * (float) inCircle / 100000000.0;
            inCircle = 0;
        }
        
        // Calculate pi
        piEstimate /= trials;
        
        // print results
        System.out.println("Pi is approximately: " + piEstimate);
    }
}