array_rotation.py

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Python Program for Reversal algorithm for array rotation
Last Updated: 29-04-2020
Write a function rotate(arr[], d, n) that rotates arr[] of size n by d elements.
Example :

Input :  arr[] = [1, 2, 3, 4, 5, 6, 7]
         d = 2
Output : arr[] = [3, 4, 5, 6, 7, 1, 2] 
Array

Rotation of the above array by 2 will make array

ArrayRotation1




Recommended: Please solve it on “PRACTICE ” first, before moving on to the solution.
# Python program for reversal algorithm of array rotation 
  
# Function to reverse arr[] from index start to end 
def rverseArray(arr, start, end): 
    while (start < end): 
        temp = arr[start] 
        arr[start] = arr[end] 
        arr[end] = temp 
        start += 1
        end = end-1
  
# Function to left rotate arr[] of size n by d 
def leftRotate(arr, d): 
    n = len(arr) 
    rverseArray(arr, 0, d-1) 
    rverseArray(arr, d, n-1) 
    rverseArray(arr, 0, n-1) 
  
# Function to print an array 
def printArray(arr): 
    for i in range(0, len(arr)): 
        print (arr[i]) 
  
# Driver function to test above functions 
arr = [1, 2, 3, 4, 5, 6, 7] 
leftRotate(arr, 2) # Rotate array by 2 
printArray(arr)