I am trying to print all possible sub array from define list. For doing that I am using below code

static void printSubArray(int arr[]) {
        int n = arr.length;

        for (int i = 0; i < n; i  ) {
            for (int j = i; j < n; j  ) {
                for (int k = i; k <= j; k  ) {
                    System.out.print(arr[k]   " ");
                }

                System.out.println();
            }
        }
    }

Tried above code some extend its working but not printing all the possible array. For example please find below example:

Input:: int a[] = { 1, 2, 3 };

Output::

1 
1 2 
1 2 3 
2 
2 3 
3 

As we can see in the output few of the subarray is missing like 1, 3.

Can some one please help on this

CodePudding user response：

There is a difference betweek subarray and subsequence {1,3} is not a subarray . It has to be continuous

Read the below article https://www.geeksforgeeks.org/subarraysubstring-vs-subsequence-and-programs-to-generate-them/

CodePudding user response：

So a current number should be printed in its line, then it is excluded and all the following numbers are printed, with the current number passed on as a prefix to be included in further printings.

The number of sets is 2ⁿ - 1, where n is the length of the input array.

Thus, the following recursive solution can be developed:

static void printSubArray(int ... arr) {
    printSubArray("", -1, arr);
}

static void printSubArray(String prefix, int ix, int ... arr) {
    for (int i = ix   1; i < arr.length; i  ) {
        System.out.println(prefix   arr[i]);
        printSubArray(prefix   arr[i]   " ", i, arr);
    }
}

For the input printSubArray(1, 2, 3) it prints:

1
1 2
1 2 3
1 3
2
2 3
3

For the input printSubArray(1, 2, 3, 4) it prints:

1
1 2
1 2 3
1 2 3 4
1 2 4
1 3
1 3 4
1 4
2
2 3
2 3 4
2 4
3
3 4
4