Data commit

Task/Two-bullet-roulette/Java/two-bullet-roulette.java

@@ -0,0 +1,156 @@
+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 Situation { A, B, C, D }
+
+enum ResultState { ALIVE, DEAD }
+
+/**
+ * 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;
+	
+}