Two bullet roulette: Difference between revisions

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import java.util.BitSet;

import java.util.concurrent.ThreadLocalRandom;

public class TwoBulletRoulette {

public static void main(String[] aArgs) {

Revolver handgun = new Revolver();

final int simulationCount = 100_000;

for ( Situation situation : Situation.values() ) {

double deaths = 0.0;

for ( int i = 0; i < simulationCount; i++ ) {

ResultState resultState = handgun.operateInMode(situation);

if ( resultState == ResultState.DEAD) {

deaths += 1.0;

}

}

final double deathRate = ( deaths / simulationCount ) * 100;

String percentage = String.format("%4.1f%%", deathRate);

System.out.println("Situation " + situation + " produces " + percentage + " deaths");

}

}

}

enum ResultState { ALIVE, DEAD }

enum Situation { A, B, C, D }

/**

* Representation of a six cylinder revolving chamber pistol.

*/

class Revolver {

public Revolver() {

chambers = new BitSet(chamberCount);

random = ThreadLocalRandom.current();

}

public ResultState operateInMode(Situation aSituation) {

return switch ( aSituation ) {

case A -> useSituationA();

case B -> useSituationB();

case C -> useSituationC();

case D -> useSituationD();

};

}

// PRIVATE //

private void unload() {

chambers.clear();

}

private void load() {

while ( chambers.get(loadingChamber) ) {

rotateClockwise();

}

chambers.set(loadingChamber);

rotateClockwise();

}

private void spin() {

final int spins = random.nextInt(0, chamberCount);

for ( int i = 0; i < spins; i++ ) {

rotateClockwise();

}

}

private boolean fire() {

boolean fire = chambers.get(firingChamber);

chambers.set(firingChamber, false);

rotateClockwise();

return fire;

}

private void rotateClockwise() {

final boolean temp = chambers.get(chamberCount - 1);

for ( int i = chamberCount - 2; i >= 0; i-- ) {

chambers.set(i + 1, chambers.get(i));

}

chambers.set(firingChamber, temp);

}

private ResultState useSituationA() {

unload();

load();

spin();

load();

spin();

if ( fire() ) {

return ResultState.DEAD;

};

spin();

if ( fire() ) {

return ResultState.DEAD;

};

return ResultState.ALIVE;

}

private ResultState useSituationB() {

unload();

load();

spin();

load();

spin();

if ( fire() ) {

return ResultState.DEAD;

};

if ( fire() ) {

return ResultState.DEAD;

};

return ResultState.ALIVE;

}

private ResultState useSituationC() {

unload();

load();

load();

spin();

if ( fire() ) {

return ResultState.DEAD;

};

spin();

if ( fire() ) {

return ResultState.DEAD;

};

return ResultState.ALIVE;

}

private ResultState useSituationD() {

unload();

load();

load();

spin();

if ( fire() ) {

return ResultState.DEAD;

};

if ( fire() ) {

return ResultState.DEAD;

};

return ResultState.ALIVE;

}

private BitSet chambers;

private ThreadLocalRandom random;

private final int firingChamber = 0;

private final int loadingChamber = 1;

private final int chamberCount = 6;

}

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