Java Program to Print all possible rotations of a given Array

Given an integer array arr[] of size N, the task is to print all possible rotations of the array.
Examples:

Input: arr[] = {1, 2, 3, 4} 
Output: {1, 2, 3, 4}, {4, 1, 2, 3}, {3, 4, 1, 2}, {2, 3, 4, 1} 
Explanation: 
Initial arr[] = {1, 2, 3, 4} 
After first rotation arr[] = {4, 1, 2, 3} 
After second rotation arr[] = {3, 4, 1, 2} 
After third rotation arr[] = {2, 3, 4, 1} 
After fourth rotation, arr[] returns to its original form.
Input: arr[] = [1] 
Output: [1] 

Approach:
Follow the steps below to solve the problem:  

1. Generate all possible rotations of the array, by performing a left rotation of the array one by one.
2. Print all possible rotations of the array until the same rotation of array is encountered.

Below is the implementation of the above approach : 

Java

// Java program to print
// all possible rotations
// of the given array
class GFG{

// Global declaration of array
static int arr[] = new int[10000];

// Function to reverse array
// between indices s and e
public static void reverse(int arr[],
                           int s, int e)
{
    while(s < e)
    {
        int tem = arr[s];
        arr[s] = arr[e];
        arr[e] = tem;
        s = s + 1;
        e = e - 1;
    }
}

// Function to generate all
// possible rotations of array
public static void fun(int arr[], int k)
{
    int n = 4 - 1;
    int v = n - k;

    if (v >= 0)
    {
        reverse(arr, 0, v);
        reverse(arr, v + 1, n);
        reverse(arr, 0, n);
    }
}

// Driver code
public static void main(String args[])
{
    arr[0] = 1;
    arr[1] = 2;
    arr[2] = 3;
    arr[3] = 4;

    for(int i = 0; i < 4; i++)
    {
        fun(arr, i);

        System.out.print("[");
        for(int j = 0; j < 4; j++)
        {
            System.out.print(arr[j] + ", ");
        }
        System.out.print("]");
    }
}
}

// This code is contributed by gk74533

Output:

[1, 2, 3, 4] [4, 1, 2, 3] [2, 3, 4, 1] [3, 4, 1, 2]

Time Complexity: O (N²)
Auxiliary Space: O (1)

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