Trust Coding : Programming: Write a program in C to rotate the elements of an array to the right by one position (last element becomes first)

Rotate Array Elements to the Right by One Position in C

In this tutorial, we will write a C program to rotate the elements of an array to the right by one position.

Problem Statement

Write a C program to rotate the elements of an array to the right by one position. After rotation:

The last element becomes the first element.
All other elements shift one position to the right.

Example

Original Array: 1 2 3 4 5
After Rotation: 5 1 2 3 4

Algorithm

Store the last element in a temporary variable.
Shift all elements one position to the right.
Place the stored element at index 0.

C Program


#include <stdio.h>

int main() {
    int arr[100], n, i;
    int temp;

    printf("Enter number of elements: ");
    scanf("%d", &n);

    printf("Enter %d elements:\n", n);
    for(i = 0; i < n; i++) {
        scanf("%d", &arr[i]);
    }

    if(n < 1) {
        printf("Rotation not possible.\n");
        return 0;
    }

    // Store last element
    temp = arr[n - 1];

    // Shift elements to the right
    for(i = n - 1; i > 0; i--) {
        arr[i] = arr[i - 1];
    }

    // Place last element at first position
    arr[0] = temp;

    printf("Array after right rotation by 1 position:\n");
    for(i = 0; i < n; i++) {
        printf("%d ", arr[i]);
    }

    return 0;
}

Explanation

Step 1: Store Last Element


temp = arr[n - 1];

We save the last element because it will be moved to the first position.

Step 2: Shift Elements


for(i = n - 1; i > 0; i--) {
    arr[i] = arr[i - 1];
}

Each element shifts one position to the right.

Step 3: Assign First Position


arr[0] = temp;

Finally, the stored last element becomes the first element.

Sample Input

Enter number of elements: 5
Enter 5 elements:
1 2 3 4 5

Output

Array after right rotation by 1 position:
5 1 2 3 4

Time Complexity

The program uses a single loop to shift elements. Therefore, the time complexity is O(n).

Trust Coding : Programming

Write a program in C to rotate the elements of an array to the right by one position (last element becomes first)