Array Rotation in C

Array rotation in C

Array rotation in C

In this Article we’ll be learning about program for array 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.

Method Discussed :

  • 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.
Array Rotation in C Programming

Method 1 : Code in C

//Write a program for array rotation in C
#include <stdio.h>
 
/* 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++)
        printf("%d ", 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.

Method 2 : Code in C

//Write a program for array rotation in C
#include <stdio.h>
 
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++)
        printf("%d ", arr[i]);

    return 0;
}

Output

40 50 60 70 10 20 30