1. 2
   3
   4

2. 

public class Question2 {
	public static double findNext(double x, double[] a) {
		double y = Double.POSITIVE_INFINITY;
		for (int i = 0; i < a.length; i++) {
			if (a[i] > x && a[i] < y)
				y = a[i];
		}
		return y;
	}

    public static void main(String[] args) {
		double x   = Double.parseDouble(args[0]);
		double[] a = new double[args.length-1];
		for (int i = 1; i < args.length; i++) {
			a[i-1] = Double.parseDouble(args[i]);
		}
		System.out.println(findNext(x, a));
    }
}

3.

public class Card {
	private double saldo;
	private long validTo;

	private static long   TICKET_VALIDITY = 5400000;
	private static double TICKET_PRICE    = 22;
	private static double SALDO_LIMIT     = -20;

	public Card(double saldo) {
		this.saldo   = saldo;
		this.validTo = System.currentTimeMillis()-1;
	}

	public void load(double credit) {
		saldo += credit;
	}

	public double getSaldo() {
		return saldo;
	}

	public long validTo() {
		return validTo;
	}

	public Status stamp() {
		long time = System.currentTimeMillis();
		if (time < validTo)
			return Status.BYTE;

		if (saldo - TICKET_PRICE < SALDO_LIMIT)
			return Status.FAIL;

		validTo = time + TICKET_VALIDITY;
		saldo -= TICKET_PRICE;
		return Status.OK;
	}
}

4.

public static int pow(int x, int n) {
	int p = 1;
	while (n > 0) {
		if (n % 2 != 0) {
			p = p * x;
		}
		x = x * x;
		n = n / 2;
	}
	return p;
}

5.

   public static List<String> getCheapestFlight(String src, String  dst)
throws FileNotFoundException {
		List<String> flights = new ArrayList<String>();

		int minPrice = Integer.MAX_VALUE;

		Scanner scanner = new Scanner("flights.txt");
		while (scanner.hasNext()) {
			String src1   = scanner.next();
			String dst1   = scanner.next();
			String flight = scanner.next();
			int    price  = scanner.nextInt();
			
			if (src.equals(src1) && dst.equals(dst1)) {
				if (minPrice > price) {
					minPrice = price;
					flights.clear();
				}
				if (minPrice == price) {
					flights.add(flight);
				}
			}
		}
		return flights;
	}