Python program to right rotate the elements of an array

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 Python program to right rotate the elements of an array

In this program, we need to rotate the elements of array towards its right by the specified number of times. An array is said to be right rotated if all elements of the array are moved to its right by one position. One approach is to loop through the array by shifting each element of the array to its next position. The last element of the array will become the first element of the rotated array.

 

Consider above array, if n is 1 then, all elements of the array will be moved to its right by one position that is the first element of the array will take the second position, the second element will be moved to the third position and so on. The last element of the array will become the first element of the array.

ALGORITHM:

  • STEP 1: Declare and initialize an array.
  • STEP 2: Variable n will denote the number of times an array should be rotated toward its right.
  • STEP 3: The array can be right rotated by shifting its elements to a position next to them which can be accomplished by looping through the array in reverse order (loop will start from the length of the array -1 to 0) and perform the operation arr[j] = arr[j-1].
  • STEP 4: The last element of the array will become the first element of the rotated array.

PROGRAM:

  1. #Initialize array   
  2. arr = [12345];
  3. #n determine the number of times an array should be rotated  
  4. n = 3;
  5. #Displays original array  
  6. print(“Original array: “);
  7. for i in range(0, len(arr)):
  8.     print(arr[i]),
  9. #Rotate the given array by n times toward right  
  10. for i in range(0, n):
  11.     #Stores the last element of array  
  12.     last = arr[len(arr)-1];
  13.     for j in range(len(arr)-1, –1, –1):
  14.         #Shift element of array by one  
  15.         arr[j] = arr[j-1];
  16.     #Last element of the array will be added to the start of the array.  
  17.     arr[0] = last;
  18. print();
  19. #Displays resulting array after rotation  
  20. print(“Array after right rotation: “);
  21. for i in range(0, len(arr)):
  22.     print(arr[i]),

Output:

Original Array:
1   2   3   4   5
Array after right rotation:
3   4   5   1   2

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