Rotation of an array using O(1) Space Complexity Python

PROGRAM TO ROTATE AN ARRAY USING REVERSAL ALGORITHM

# 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):

  

    if d == 0:

        return

    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]

n = len(arr)

d = 2

  

# in case the rotating factor is 

# greater than array length

d = d % n      

leftRotate(arr, d) # Rotate array by 2

printArray(arr)

OUTPUT

3 4 5 6 7 1 2