HouseEdge.java

package com.bustabit;

import java.io.BufferedReader;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.InputStreamReader;
import java.lang.reflect.Type;
import java.util.List;

import com.google.gson.Gson;
import com.google.gson.reflect.TypeToken;

public class HouseEdge {

	public static double prob(double c) {
		return (99D/101D) * (1D/(c-1D/100D));
	}

	public static boolean game(double cashout) {
		final double r = Math.random();
		final double p = prob(cashout);
		return r <= p;
	}

	public static double bet(double cashout, double amount) {
		return amount*.01 + (game(cashout) ? amount * cashout : 0);
	}

	public static double cashout(List<HistogramBin> histogram) {
		double r = Math.random();
		for(int i = 0; i<histogram.size(); i++) {
			if(r < histogram.get(i).getCumulative()) {
				return histogram.get(i).getCashout();
			}
		}

		return 1.0;
	}

	// args[0] is path to CashoutHistogram.json
	public static void main(String[] args) {
		FileInputStream fstream;

		try {
			fstream = new FileInputStream(args[0]);
		} catch (FileNotFoundException e) {
			e.printStackTrace();
			return;
		}

		BufferedReader br = new BufferedReader(new InputStreamReader(fstream));

		Type listType = new TypeToken<List<HistogramBin>>() {}.getType();

		List<HistogramBin> histogram = new Gson().fromJson(br, listType);

		double bets = 0;
		double paid = 0;

		for(int i=0; i<1000000000; i++) {
			if(i%10000000 == 0) System.out.println(i);
			bets += 1000;
			double cashout = cashout(histogram);
			paid += bet(cashout, 1000D);
		}

		System.out.println("House Edge: " + (1 - paid/bets));

	}
}