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 program to print
# all possible rotations
# of the given array
# Function to reverse array
# between indices s and e
def reverse(arr, s, e):
while s < e:
tem = arr[s]
arr[s] = arr[e]
arr[e] = tem
s = s + 1
e = e - 1
# Function to generate all
# possible rotations of array
def fun(arr, k):
n = len(arr)-1
# k = k % n
v = n - k
if v>= 0:
reverse(arr, 0, v)
reverse(arr, v + 1, n)
reverse(arr, 0, n)
return arr
# Driver Code
arr = [1, 2, 3, 4]
for i in range(0, len(arr)):
count = 0
p = fun(arr, i)
print(p, end =" ")
# Python program to print# all possible rotations# of the given array# Function to reverse array # between indices s and edef reverse(arr, s, e): while s < e: tem = arr[s] arr[s] = arr[e] arr[e] = tem s = s + 1 e = e - 1# Function to generate all# possible rotations of arraydef fun(arr, k): n = len(arr)-1 # k = k % n v = n - k if v>= 0: reverse(arr, 0, v) reverse(arr, v + 1, n) reverse(arr, 0, n) return arr# Driver Codearr = [1, 2, 3, 4]for i in range(0, len(arr)): count = 0 p = fun(arr, i) print(p, end =" ")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 :
class Main:
def main(args):
arr = [1, 2, 3, 4]
n = len(arr)
rotatedArr = [0] * (2*n)
# Copy the array twice into the rotatedArr
for i in range(n):
rotatedArr[i] = arr[i]
rotatedArr[i+n] = arr[i]
# Generate all possible rotations
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="")
# Nikunj Sonigara
if __name__ == "__main__":
Main.main(None)
class Main: def main(args): arr = [1, 2, 3, 4] n = len(arr) rotatedArr = [0] * (2*n) # Copy the array twice into the rotatedArr for i in range(n): rotatedArr[i] = arr[i] rotatedArr[i+n] = arr[i] # Generate all possible rotations 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="")# Nikunj Sonigaraif __name__ == "__main__": Main.main(None)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)
