# Right rotation of an array

Given an array, right rotate it by k elements.

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:

• C++

`// C++ program for right rotation of`

`// an array (Reversal Algorithm)`

`#include <bits/stdc++.h>`

`/*Function to reverse arr[]`

`from index start to end*/`

`void` `reverseArray(` `int` `arr[], ` `int` `start,`

`` `int` `end)`

`{`

`` `while` `(start < end)`

`` `{`

`` `std::swap(arr[start], arr[end]);`

`` `start++;`

`` `end--;`

`` `}`

`}`

`/* Function to right rotate arr[]`

`of size n by d */`

`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 */`

`void` `printArray(` `int` `arr[], ` `int` `size)`

`{`

`` `for` `(` `int` `i = 0; i < size; i++)`

`` `std::cout << arr[i] << ` `" "` `;`

`}`

`// driver code`

`int` `main()`

`{`

`` `int` `arr[] = {1, 2, 3, 4, 5,`

`` `6, 7, 8, 9, 10};`

``

`` `int` `n = ` `sizeof` `(arr)/` `sizeof` `(arr[0]);`

`` `int` `k = 3;`

``

`` `rightRotate(arr, k, n);`

`` `printArray(arr, n);`

`` `return` `0;`

`}`

Output:

8 9 10 1 2 3 4 5 6 7