Python Program for Array Rotation Example
Partitioning the sub arrays and reversing them
Approach:
Input arr[] = [1, 2, 3, 4, 5, 6, 7, 8], d = 1, size = 8
1) Reverse the entire list by swapping first and last numbers
i.e start=0, end=size-1
2) Partition the first subarray and reverse the first subarray, by swapping first and last numbers.
i.e start=0, end=size-d-1
3) Partition the second subarray and reverse the second subarray, by swapping first and last numbers.
i.e start=size-d, end=size-1
Example:
Python3
# Python program to left-rotate the given array# Function reverse the given array# by swapping first and last numbers.def reverse(start, end, arr): # No of iterations needed for reversing the list no_of_reverse = end-start+1 # By incrementing count value swapping # of first and last elements is done. count = 0 while((no_of_reverse)//2 != count): arr[start+count], arr[end-count] = arr[end-count], arr[start+count] count += 1 return arr# Function takes array, length of# array and no of rotations as inputdef left_rotate_array(arr, size, d): # Reverse the Entire List start = 0 end = size-1 arr = reverse(start, end, arr) # Divide array into twosub-array # based on no of rotations. # Divide First sub-array # Reverse the First sub-array start = 0 end = size-d-1 arr = reverse(start, end, arr) # Divide Second sub-array # Reverse the Second sub-array start = size-d end = size-1 arr = reverse(start, end, arr) return arrarr = [1, 2, 3, 4, 5, 6, 7, 8]size = 8d = 1print('Original array:', arr)# Finding all the symmetric rotation numberif(d <= size): print('Rotated array: ', left_rotate_array(arr, size, d))else: d = d % size print('Rotated array: ', left_rotate_array(arr, size, d))# This code contributed by SR.Dhanush |
Output
Original array: [1, 2, 3, 4, 5, 6, 7, 8] Rotated array: [2, 3, 4, 5, 6, 7, 8, 1]
Time Complexity: O(log10(Half no of elements presents in the given array)).
Auxiliary Space: O(1).
Python Program for Array Rotation
Here we are going to see how we can rotate array with Python code.
Array Rotation: