Python program to left rotate the elements of an array

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Python program to left rotate the elements of an array

In this program, we need to rotate the elements of an array towards the left by the specified number of times. In the left rotation, each element of the array will be shifted to its left by one position and the first element of the array will be added to end of the list. This process will be followed for a specified number of times.

 

Consider above array, if n is 1 then, all elements of the array will be moved to its left by one position such that second element of the array will take the first position, the third element will be moved to the second position and so on. The first element of the array will be added to the last 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 left.
  • STEP 3: The array can be left rotated by shifting its elements to a position prior to them which can be accomplished by looping through the array and perform the operation arr[j] = arr[j+1].
  • STEP 4: The first element of the array will be added to the last 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 left  
  10. for i in range(0, n):
  11.     #Stores the first element of the array  
  12.     first = arr[0];
  13.     for j in range(0, len(arr)-1):
  14.         #Shift element of array by one  
  15.         arr[j] = arr[j+1];
  16.     #First element of array will be added to the end  
  17.     arr[len(arr)-1] = first;
  18. print();
  19. #Displays resulting array after rotation  
  20. print(“Array after left rotation: “);
  21. for i in range(0, len(arr)):
  22.     print(arr[i]),

Output:

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

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