*894*

Question:Write a program to rotate an array arr[], having a size ‘n’ by ‘d’ elements?

Input:arr[] = { 4, 8, 15, 16, 23, 42, 99 }, d = 3

Output:16, 23, 42, 99, 4, 8, 15

Let us suppose our array is in this way:

On rotating the array by 3 elements, it should look like:

To solve the above problem, we can adopt this following technique-

- Create a function that rotates the entire array by one element at a time.
- To rotate by one, store arr[0] in a temporary variable temp, move arr[1] to arr[0], arr[2] to arr[1] â€¦and finally temp to arr[n-1]
- Create a function rotate(arr[], d, n) that calls the above function ‘d’ number of times.

Here is an implementation of the above algorithm:-

#include<stdio.h> //function to rotate the array by one element void leftRotatebyOne(int arr[], int n) { int i, temp; temp = arr[0]; //swap all the elements for (i = 0; i < n-1; i++) arr[i] = arr[i+1]; arr[i] = temp; } /*Function to left rotate arr[] of size n by d*/ void leftRotate(int arr[], int d, int n) { int i; //call the function to rotate by 1, d number of times for (i = 0; i < d; i++) leftRotatebyOne(arr, n); } //utility function to print an array void printArray(int arr[], int size) { int i; for(i = 0; i < size; i++) printf("%d ", arr[i]); } //Driver program to test above functions int main(void) { int arr[] = {4, 8, 15, 16, 23, 42, 99}; leftRotate(arr, 3, 7); printArray(arr, 7); return 0; }

*Time Complexity:* O(n * d)

* Space Complexity:* O(1)