public class Monty {
    public static void main(String[] args) {
        int switchWins = 0;
        int stayWins = 0;
        // Repeat game a million times
        for (int rep = 0; rep < 1e6; rep++) {
            int prize = (int)(Math.random() * 3 + 1);
            int guess = 1;
            // Which door is opened?
            int open; 
            if (prize == 1) {
                open = (int)(Math.random() * 2 + 2);
            } else if (prize == 2) {
                open = 3;
            } else  { // (prize is 3)
                open = 2;
            }
            // Which door do we switch to?
            // open is never 1
            int switchDoor;
            if (open == 2) {
                switchDoor = 3;
            } else { // (open is 3)
                switchDoor = 2;
            }
            // Do we win if we switch?
            if (switchDoor == prize) {
                switchWins++;
            }
            // Do we win if we stay?
            if (guess == prize) {
                stayWins++;
            }
        }
        System.out.println("Switch wins: " + switchWins);
        System.out.println("Stay wins: " + stayWins);
    }
}