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C++ Program to Print all possible rotations of a given Array

  • Last Updated : 11 Feb, 2022

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:  

  1. Generate all possible rotations of the array, by performing a left rotation of the array one by one.
  2. Print all possible rotations of the array until the same rotation of array is encountered.

Below is the implementation of the above approach : 

C++




// C++ program to print
// all possible rotations
// of the given array
#include <iostream>
using namespace std;  
 
// Global declaration of array
int arr[10000];
 
// Function to reverse array
// between indices s and e
void reverse(int arr[],
             int s, int e)
{
  while(s < e)
  {
    int tem = arr[s];
    arr[s] = arr[e];
    arr[e] = tem;
    s = s + 1;
    e = e - 1;
  }
}
 
// Function to generate all
// possible rotations of array
void fun(int arr[], int k)
{
  int n = 4 - 1;
  int v = n - k;
 
  if (v >= 0)
  {
    reverse(arr, 0, v);
    reverse(arr, v + 1, n);
    reverse(arr, 0, n);
  }
}
 
// Driver code
int main()
{
  arr[0] = 1;
  arr[1] = 2;
  arr[2] = 3;
  arr[3] = 4;
 
  for(int i = 0; i < 4; i++)
  {
    fun(arr, i);
    cout << ("[");
     
    for(int j = 0; j < 4; j++)
    {
      cout << (arr[j]) << ", ";
    }
    cout << ("]");
  }
}
 
// This code is contributed by Princi Singh
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)

Please refer complete article on Print all possible rotations of a given Array for more details!
 


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