Below is the syntax highlighted version of MonteHall.java
from §1.3 Conditionals and Loops.
/****************************************************************************** * Compilation: javac MonteHall.java * Execution: java MonteHall trials * * Plays the Monte Hall game the specified number of times with the * switching strategy and reports the fraction of games won. * * Sample execution: * * % java MonteHall 10000000 * Fraction of games won = 0.666586 * * * Note: true winning probability = 2/3. * ******************************************************************************/ public class MonteHall { public static void main(String[] args) { int trials = Integer.parseInt(args[0]); // # trials int wins = 0; // # times you win by switching // repeat experiment trials times for (int i = 0; i < trials; i++) { // host hides prize behind 1 of 3 doors uniformly at random int prize = (int) (3 * Math.random()); // contestant selects 1 of 3 doors uniformly at random int choice = (int) (3 * Math.random()); // at random, host reveals an unchosen door not containing prize int reveal; do { reveal = (int) (3 * Math.random()); } while ((reveal == choice) || (reveal == prize)); // hack to compute the remaining door which contestent switches to int other = 0 + 1 + 2 - reveal - choice; // switching leads to a win if (other == prize) wins++; } // avoid integer division System.out.println("Fraction of games won = " + 1.0 * wins / trials); } }