Perform right rotation on array by two positions in Python

Python program to perform right rotation of array (list) elements by two positions

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:

perform right rotation on array by 2 in python

After two rotations:

perform right rotation on array by 2 in python

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)

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

Step 1: Start

Step 2: take an input from the user (let’s say size).

Step 3: Create an empty list and a variable sum with value assign is 0.

Step 4: for i in range(0,size):

                   elem=int(input(“Please give value for index “+str(i)+”: “))

                   arr.append(elem)

Step 5: for i in range(0,2):

    temp=arr[size-1];

    for j in range(size-1,-1,-1):

            arr[j]=arr[j-1]

   arr[0]=temp;

Step 6: print arr

Step 7: Stop

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

Output :

perform right rotation by 2 in python array

Explanation:

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

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

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