Python3 Program to Print all possible rotations of a given Array
Given an integer array arr[] of size N, the task is to print all possible rotations of the array.
Examples:
Input: arr[] = {1, 2, 3, 4}
Output: {1, 2, 3, 4}, {4, 1, 2, 3}, {3, 4, 1, 2}, {2, 3, 4, 1}
Explanation:
Initial arr[] = {1, 2, 3, 4}
After first rotation arr[] = {4, 1, 2, 3}
After second rotation arr[] = {3, 4, 1, 2}
After third rotation arr[] = {2, 3, 4, 1}
After fourth rotation, arr[] returns to its original form.
Input: arr[] = [1]
Output: [1]
Approach:
Follow the steps below to solve the problem:
- Generate all possible rotations of the array, by performing a left rotation of the array one by one.
- Print all possible rotations of the array until the same rotation of array is encountered.
Below is the implementation of the above approach :
Python
def reverse(arr, s, e):
while s < e:
tem = arr[s]
arr[s] = arr[e]
arr[e] = tem
s = s + 1
e = e - 1
def fun(arr, k):
n = len (arr) - 1
v = n - k
if v> = 0 :
reverse(arr, 0 , v)
reverse(arr, v + 1 , n)
reverse(arr, 0 , n)
return arr
arr = [ 1 , 2 , 3 , 4 ]
for i in range ( 0 , len (arr)):
count = 0
p = fun(arr, i)
print (p, end = " " )
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Output:
[1, 2, 3, 4] [4, 1, 2, 3] [2, 3, 4, 1] [3, 4, 1, 2]
Time Complexity: O (N2)
Auxiliary Space: O (1)
Approach 2: Follow the steps below to solve the problem:
- Define the Main class.
- Define the main method which takes args as input.
- Create the arr array and get its length n.
- Create the rotatedArr array with length 2*n and fill it with zeroes.
- Copy the arr array twice into the rotatedArr array.
- Loop over the n possible rotations.
- For each rotation, print a “[” character.
- Loop over the elements of the rotated array.
- Print each element followed by a space (if it’s not the last element in the rotated array).
- After the loop, print a “]” character followed by a space.
- Run the main method if the script is being executed as the main module.
Below is the implementation of the above approach :
Python3
class Main:
def main(args):
arr = [ 1 , 2 , 3 , 4 ]
n = len (arr)
rotatedArr = [ 0 ] * ( 2 * n)
for i in range (n):
rotatedArr[i] = arr[i]
rotatedArr[i + n] = arr[i]
for i in range (n):
print ( "[" , end = "")
for j in range (i, i + n):
print (rotatedArr[j], end = "")
if j ! = i + n - 1 :
print ( " " , end = "")
print ( "] " , end = "")
if __name__ = = "__main__" :
Main.main( None )
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Output
[1 2 3 4] [2 3 4 1] [3 4 1 2] [4 1 2 3]
Time Complexity: O(N2)
Auxiliary Space: O(N)
Last Updated :
18 May, 2023
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