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# Java Program for Reversal algorithm for right rotation of an array

Given an array, right rotate it by k elements.

After K=3 rotation

Examples:

```Input: arr[] = {1, 2, 3, 4, 5,
6, 7, 8, 9, 10}
k = 3
Output: 8 9 10 1 2 3 4 5 6 7

Input: arr[] = {121, 232, 33, 43 ,5}
k = 2
Output: 43 5 121 232 33```

Note : In the below solution, k is assumed to be smaller than or equal to n. We can easily modify the solutions to handle larger k values by doing k = k % n
Algorithm:

```rotate(arr[], d, n)
reverseArray(arr[], 0, n-1) ;
reverse(arr[], 0, d-1);
reverse(arr[], d, n-1);```

Below is the implementation of above approach:

## Java

 `// Java program for right rotation of``// an array (Reversal Algorithm)``import` `java.io.*;` `class` `GFG``{``    ``// Function to reverse arr[]``    ``// from index start to end``    ``static` `void` `reverseArray(``int` `arr[], ``int` `start,``                             ``int` `end)``    ``{``        ``while` `(start < end)``        ``{``           ``int` `temp = arr[start];``           ``arr[start] = arr[end];``           ``arr[end] = temp;``           ``start++;``           ``end--;``         ``}``    ``}` `    ``// Function to right rotate``    ``// arr[] of size n by d``    ``static` `void` `rightRotate(``int` `arr[], ``int` `d, ``int` `n)``    ``{``       ``reverseArray(arr, ``0``, n - ``1``);``       ``reverseArray(arr, ``0``, d - ``1``);``       ``reverseArray(arr, d, n - ``1``);``    ``}` `    ``// Function to print an array``    ``static` `void` `printArray(``int` `arr[], ``int` `size)``    ``{``       ``for` `(``int` `i = ``0``; i < size; i++)``          ``System.out.print(arr[i] + ``" "``);``    ``}` `    ``public` `static` `void` `main (String[] args)``    ``{``        ``int` `arr[] = {``1``, ``2``, ``3``, ``4``, ``5``,``                     ``6``, ``7``, ``8``, ``9``, ``10``};``    ` `    ``int` `n = arr.length;``    ``int` `k = ``3``;``    ` `    ``rightRotate(arr, k, n);``    ``printArray(arr, n);``        ` `    ``}``}``// This code is contributed by Gitanjali.`

Output:

`8 9 10 1 2 3 4 5 6 7 `

Time Complexity: O(N)

Auxiliary Space: O(1)

Please refer complete article on Reversal algorithm for right rotation of an array for more details!

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