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import java.util.ArrayList;

public class Main
{
	public static void main(String[] args)
	{
		ArrayList<ArrayList<Integer>> result = new ArrayList<ArrayList<Integer>>();
		function(new int[] { 1, 2, 3, 4, 5 }, 0, new ArrayList<Integer>(), result);
		for (ArrayList<Integer> list : result) {
			System.out.println(list.toString());
		}
	}

	public static void function(int[] numbers, int index, ArrayList<Integer> taken, ArrayList<ArrayList<Integer>> result) {
		if (index == numbers.length)
			result.add(taken);
		else {
			function(numbers, index + 1, taken, result); //do not take the current number
			ArrayList<Integer> copy = new ArrayList<>(taken);
			copy.add(numbers[index]);
			function(numbers, index + 1, copy, result); //take it
		}
	}
}

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import java.util.Arrays;

public class Main
{
	public static void main(String[] args)
	{
		function(0, new boolean[5]);
	}

	public static void function(int index, boolean[] taken) {
		if (index == taken.length) {
			System.out.println(Arrays.toString(taken));
		}
		else {
			function(index + 1, taken); //do not take the current number
			taken[index] = true;
			function(index + 1, taken); //take it
			taken[index] = false;
		}
	}
}

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public class Main {
	public static void teilmengen(int[] menge, boolean[] enthalten, int k, int n) {
		if (k == enthalten.length) {
			for (int i = 0; i < enthalten.length; i++)
				if (enthalten[i])
					System.out.print(menge[i] + " ");
			System.out.println();
		}
		else {
			teilmengen(menge, enthalten, k + 1, n);
			enthalten[k] = true;
			teilmengen(menge, enthalten, k + 1, n);
			enthalten[k] = false;
		}
	}

	public static void main(String[] args) {
		int[] mengeA = { -1, 1, 2, 3, 4 };
		boolean[] enthaltenA = new boolean[5];
		teilmengen(mengeA, enthaltenA, 0, 4);
	}
}