Run Monty Hall Problem with Random

MontyHallProblem.java

import java.security.*;
import java.util.*;
import java.util.concurrent.atomic.*;
public class MontyHallProblem {
    //private static final long COUNT = 1048576L;
    private static final long COUNT = 30000L;
    static { assert COUNT > 0L; }
    private static final int DOORS = 3;
    static { assert DOORS > 0; }
    public static void main(final String... args) throws Exception {
	final LongAdder adder = new LongAdder();
	final SecureRandom random = SecureRandom.getInstanceStrong();
	final List<Boolean> doors = new ArrayList<Boolean>(DOORS);
	for (long i = 0L; i < COUNT; i++) {
	    assert doors.isEmpty();
	    {
		boolean car = false;
		for (int j = 0; j < DOORS; j++) {
		    if (car) {
			doors.add(Boolean.FALSE);
			continue;
		    }
		    doors.add(random.nextBoolean());
		    car = doors.get(doors.size() - 1);
		}
		if (!car) {
		    final int k = random.nextInt(DOORS);
		    doors.remove(k);
		    doors.add(k, Boolean.TRUE);
		}
	    }
	    final boolean one = doors.remove(random.nextInt(doors.size()));
	    if (one) { // car -> fail, cuz we gonna change anyway.
		doors.clear();
		continue;
	    }
	    // remove one of those for goats
	    for (final Iterator<Boolean> j = doors.iterator(); j.hasNext(); ) {
		final boolean car = j.next();
		if (!car) { // goat
		    j.remove();
		    break;
		}
	    }
	    // always change
	    if (doors.remove(0)) { // and it's for the car?
		adder.add(1L); // success
	    }
	}
	System.out.println(adder.doubleValue() / COUNT);
    }
}