Perform right rotation on array by two positions in Python

In this tutorial, we will learn to create an array (list in case of python) and rotate the elements stored in the array (list) by two positions using python.

 That means if our array (list) is:

After two rotations:

Problem Statement

Our program will first take the input of array (list) size and then the elements of the array (list). Then, our program will rotate the elements of the array (list) by 2.

For example:

Case 1: if the user inputs 4 as array (list) size and the array (list) elements as 1,2,3,4.

              The output should be 3, 4, 1, 2.

Case 2: if the user inputs 5 as array (list) size and the array (list) elements as 9,8,7,6,5.

              The output should be 6,5,9,8,7.

Our logic to perform right rotation on array (list) elements by two positions

• Our program will take input to fix the size of the array (list).
• Then our program will run for a ‘for loop’ to take the inputs from the user. The inputs will be the elements (or the content) of the array (list).
• Then, by using the concept of ‘nested loop’, our program will rotate the array (list) by 2 positions.
• Print the final array (list)

Python code to perform right rotation on array (list) elements by two positions

#taking the input from the user to fix the array size
size=int(input("Enter the number of elements you want in array: "))
arr=[]
# adding elements to the array (list)
for i in range(0,size):
    elem=int(input("Please give value for index "+str(i)+": "))
    arr.append(elem)
for i in range(0,2):
# storing last element of the array (list) in temp variable
    temp=arr[size-1];
    for j in range(size-1,-1,-1):
        arr[j]=arr[j-1]
# making the last element of the array, the first element
    arr[0]=temp;
print("Array after performing right rotation :")
print(arr)

Output

Enter the number of elements you want in array: 5
Please give value for index 0: 1
Please give value for index 1: 2
Please give value for index 2: 3
Please give value for index 3: 4
Please give value for index 4: 5
Array after performing right rotation :
[4, 5, 1, 2, 3]

Explanation:

For the input array (list): [1, 2, 3, 4, 5], the for loop will rotate the array 2 times.

For 1^st rotation the array becomes: [5, 1, 2, 3, 4].

And finally at 2^nd rotation the array becomes: [4, 5, 1, 2, 3]