C++ program for rotation of elements of array- left and right

February 23, 2022

Array Rotation left and right

In this Article we’ll be learning about C++ program for rotation of elements of array – left and right to a specified number of times. An array is said to be right rotated if all the selected elements were  moved towards right by one position. The last element of array will become the first element of array after rotation and vice versa for left rotation. 

Rotation of elements of array- left and right in C++
While loop in C

Here, in this page we will discuss the following two methods to rotate the array in left side.

  • Method 1 : Using Temporary array.
  • Method 2 : Rotate one by one.

Method 1 :

In this method we will declare an extra array to store some k elements. Here, k refers to number of rotations.

  • Declare a temporary array of size k.
  • Store the first k elements in temp[] array.
  • Now, shift the remaining elements.
  • After, shifting the elements add the elements of temp[] in the array.

Method 1 : Code in C++

//Write a program for array rotation in C++
#include<iostream>
using namespace std;
 
/* Driver program to test above functions */
int main()
{
    int arr[] = { 10, 20, 30, 40, 50, 60, 70};
    int n = sizeof(arr)/sizeof(arr[0]);
    int k = 3;
    
    int temp[k];
    for(int i=0; i<k; i++)
      temp[i] = arr[i];
    
    int x = k;
    for(int i=0; x < n; i++){
        arr[i] = arr[x++];
    }
    x = 0;
    
    for(int i=n-k; i<n; i++)
       arr[i] = temp[x++];
    for (int i = 0; i < n; i++)
        cout<<arr[i]<<" ";

    return 0;
}

Output

40 50 60 70 10 20 30

Method 2 :

In this method we will rotate the elements one by one by shifting them.

Time and Space Complexity :

  • Time Complexity : O(n*k)
  • Space Complexity : O(1)

Method 2 : Code in C++

//Write a program for array rotation in C++
#include <iostream>
using namespace std;

void leftRotatebyOne(int arr[], int n)
{
    int temp = arr[0], i;
    for (i = 0; i < n - 1; i++)
        arr[i] = arr[i + 1];
    arr[n-1] = temp;
}

void leftRotate(int arr[], int k, int n)
{
    for (int i = 0; i < k; i++)
        leftRotatebyOne(arr, n);
}
 
/* Driver program to test above functions */
int main()
{
    int arr[] = { 10, 20, 30, 40, 50, 60, 70};
    int n = sizeof(arr)/sizeof(arr[0]);
    
    leftRotate(arr, 3, n);
    
    for (int i = 0; i < n; i++)
        cout<< arr[i]<<" ";

    return 0;
}

Output

40 50 60 70 10 20 30
While loop in C