1. Answer: 0
           2
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           0

2. 

public class Question2 {
	public static boolean isProgression(int[] a) {
		if (a.length <= 2)
			return true;
		
		int diff = a[1]-a[0];
		for (int i = 0; i < a.length-1; i++) {
			if (a[i+1]-a[i] != diff)
				return false;
		}
		return true;
	}

	public static void main(String[] args) {
		int[] a = new int[args.length];
		for (int i = 0; i < args.length; i++) {
			a[i] = Integer.parseInt(args[i]);
		}
		System.out.println(isProgression(a));
	}
}

3.

public class Battery {
	private int power;
	private List listeners;

	public Battery(int power) {
		this.power = power;
		this.listeners = new ArrayList();
	}
	
	public void charge(int delta) {
		power += delta;
		for (Object o : listeners) {
			BatteryListener l = (BatteryListener) o;
			l.updateStatus(power);
		}
	}
	
	public void addListener(BatteryListener l) {
		listeners.add(l);
	}
}

public class TestBatteryListener implements BatteryListener {
	public void updateStatus(int power) {
		System.out.println(power);
	}
}

4.

public class Question4 {
	public static char[] generateCipher() {
		char[] alphabet = "ABCDEFGHIJKLMNOPQRSTUVWXYZ".toCharArray();
		char[] cypher = new char[26];
		for (int i = 0; i < cypher.length; i++) {
			boolean duplicate;
			do {
				cypher[i] = alphabet[(int) (Math.random()*alphabet.length)];
				duplicate = false;
				for (int j = 0; j < i; j++) {
					if (cypher[i] == cypher[j]) {
						duplicate = true;
						break;
					}
				}
			} while (duplicate);
		}
		return cypher;
	}

	public static void main(String[] args) {
		System.out.println(generateCipher());
	}
}

5.

public static boolean isEasy(File dictionary, String password) throws FileNotFoundException {
	Scanner scanner = new Scanner(dictionary);
	while (scanner.hasNext()) {
		String word = scanner.next();
		if (word.equals(password))
			return true;
	}
	return false;
}