Java Program to Generate All Possible Subsets using Gray Code Order

This is a java program to generate and print all the subsets using the Gray Code Order. The reflected binary code, also known as Gray code after Frank Gray, is a binary numeral system where two successive values differ in only one bit (binary digit). The gray code equivalent of a binary number is (number >> 1) ^ number, i.e. right-shift the number by one and EX-ORing with the original number.

Here is the source code of the Java Program to Generate All Subsets of a Given Set in the Gray Code Order. The Java program is successfully compiled and run on a Windows system. The program output is also shown below.

//This is a java program to generate all subsets of given set of numbers using gray code order

```
import java.util.Random;
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import java.util.Scanner;
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```
public class Gray_Code_Permutation 
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```
{
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    public static int[] grayCode(int N)

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    {
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        int[] grayCode = new int[(int) Math.pow(2, N)];

        int[] binary = new int[(int) Math.pow(2, N)];

```
 
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        for (int i = 0; i < Math.pow(2, N); i++)

```
            grayCode[i] = (i >> 1) ^ i;
```
```
 
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        for (int i = 0; i < Math.pow(2, N); i++)

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        {
```
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            int b = 1;
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            binary[i] = 0;
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            while (grayCode[i] > 0) 
```
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            {
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                binary[i] += (grayCode[i] % 2) * b;

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                grayCode[i] /= 2;
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                b = b * 10;
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            }
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        }
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        return binary;
```
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    }
```
```
 
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    public static void main(String args[])

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    {
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```
        Random random = new Random();
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        Scanner sc = new Scanner(System.in);

        System.out.println("Enter the number of elements in the set: ");

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        int N = sc.nextInt();
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        int[] sequence = new int[N];
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        for (int i = 0; i < N; i++)
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            sequence[i] = Math.abs(random.nextInt(100));

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        System.out.println("The elements in the set : ");

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        for (int i = 0; i < N; i++)
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            System.out.print(sequence[i] + " ");

```
 
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        int[] mask = new int[(int) Math.pow(2, N)];

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        mask = grayCode(N);
```
```
 
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        System.out.println("\nThe permutations are: ");

        for (int i = 0; i < Math.pow(2, N); i++)

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        {
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            System.out.print("{ ");
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            for (int j = 0; j < N; j++)

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            {
```
```
                if (mask[i] % 10 == 1)
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                    System.out.print(sequence[j] + " ");

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                mask[i] /= 10;
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            }
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            System.out.println("}");
```
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        }
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        sc.close();
```
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    }
```
```
}
```

Output:

$ javac Gray_Code_Permutation.java
$ java Gray_Code_Permutation
 
Enter the number of elements in the set: 
4
The elements in the set : 
36 75 15 59 
The permutations are: 
{ }
{ 36 }
{ 36 75 }
{ 75 }
{ 75 15 }
{ 36 75 15 }
{ 36 15 }
{ 15 }
{ 15 59 }
{ 36 15 59 }
{ 36 75 15 59 }
{ 75 15 59 }
{ 75 59 }
{ 36 75 59 }
{ 36 59 }
{ 59 }
 
Enter the number of elements in the set: 
3
The elements in the set : 
73 36 36 
The permutations are: 
{ }
{ 73 }
{ 73 36 }
{ 36 }
{ 36 36 }
{ 73 36 36 }
{ 73 36 }
{ 36 }

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