Minimum rotations required to get the same string

Given a string, we need to find the minimum number of rotations required to get the same string.

Examples:

Input : s = "geeks"
Output : 5

Input : s = "aaaa"
Output : 1

Recommended: Please try your approach on {IDE} first, before moving on to the solution.

The idea is based on below post.

A Program to check if strings are rotations of each other or not

Step 1 : Initialize result = 0 (Here result is count of rotations)
Step 2 : Take a temporary string equals to original string concatenated with itself.
Step 3 : Now take the substring of temporary string of size same as original string starting from second character (or index 1).
Step 4 : Increase the count.
Step 5 : Check whether the substring becomes equal to original string. If yes, then break the loop. Else go to step 2 and repeat it from the next index.

C/C++

// C++ program to determine minimum number 
// of rotations required to yield same 
// string. 
#include <iostream> 
using namespace std; 
  
// Returns count of rotations to get the 
// same string back. 
int findRotations(string str) 
{ 
    // tmp is the concatenated string. 
    string tmp = str + str; 
    int n = str.length(); 
  
    for (int i = 1; i <= n; i++) { 
  
        // substring from i index of original 
        // string size. 
        string substring = tmp.substr(i, str.size()); 
  
        // if substring matches with original string 
        // then we will come out of the loop. 
        if (str == substring) 
            return i; 
    } 
    return n; 
} 
  
// Driver code 
int main() 
{ 
    string str = "abc"; 
    cout << findRotations(str) << endl; 
    return 0; 
} 

Java

// Java program to determine minimum number 
// of rotations required to yield same 
// string. 
  
import java.util.*; 
  
class GFG 
{ 
    // Returns count of rotations to get the 
    // same string back. 
    static int findRotations(String str) 
    { 
        // tmp is the concatenated string. 
        String tmp = str + str; 
        int n = str.length(); 
      
        for (int i = 1; i <= n; i++) 
        { 
      
            // substring from i index of original 
            // string size. 
              
            String substring = tmp.substring(i, str.length()); 
      
            // if substring matches with original string 
            // then we will come out of the loop. 
            if (str == substring) 
                return i; 
        } 
        return n; 
    } 
  
    // Driver Method 
    public static void main(String[] args) 
    { 
            String str = "abc"; 
        System.out.println(findRotations(str)); 
    } 
} 
/* This code is contributed by Mr. Somesh Awasthi */

Python3

# Python 3 program to determine minimum  
# number of rotations required to yield  
# same string. 
  
# Returns count of rotations to get the 
# same string back. 
def findRotations(str): 
      
    # tmp is the concatenated string. 
    tmp = str + str
    n = len(str) 
  
    for i in range(1, n + 1): 
          
        # substring from i index of  
        # original string size. 
        substring = tmp[i: i+n] 
  
        # if substring matches with  
        # original string then we will  
        # come out of the loop. 
        if (str == substring): 
            return i 
    return n 
  
# Driver code 
if __name__ == '__main__': 
  
    str = "abc"
    print(findRotations(str)) 
  
# This code is contributed  
# by 29AjayKumar. 

C#

// C# program to determine minimum number 
// of rotations required to yield same 
// string. 
using System; 
  
class GFG { 
      
    // Returns count of rotations to get 
    // the same string back. 
    static int findRotations(String str) 
    { 
          
        // tmp is the concatenated string. 
        String tmp = str + str; 
        int n = str.Length; 
      
        for (int i = 1; i <= n; i++) 
        { 
      
            // substring from i index of 
            // original string size. 
              
            String substring =  
                 tmp.Substring(i, str.Length); 
      
            // if substring matches with 
            // original string then we will 
            // come out of the loop. 
            if (str == substring) 
                return i; 
        } 
          
        return n; 
    } 
  
    // Driver Method 
    public static void Main() 
    { 
        String str = "abc"; 
          
        Console.Write(findRotations(str)); 
    } 
} 
  
// This code is contributed by nitin mittal. 

PHP

<?php 
// PHP program to determine minimum  
// number of rotations required to  
// yield same string.  
  
// Returns count of rotations  
// to get the same string back.  
function findRotations($str)  
{  
    // tmp is the concatenated string.  
    $tmp = ($str + $str);  
    $n = strlen($str);  
  
    for ( $i = 1; $i <= $n; $i++) 
    {  
  
        // substring from i index  
        // of original string size.  
        $substring = $tmp.substr($i,  
                          strlen($str));  
  
        // if substring matches with  
        // original string then we will  
        // come out of the loop.  
        if ($str == $substring)  
            return $i;  
    }  
    return $n;  
}  
  
// Driver code  
$str = "abc";  
echo findRotations($str), "\n";  
  
// This code is contributed  
// by Sachin 
?> 

Output:

Time Complexity: O(n²)

Alternate Implementation in Python :

Python3

# Python 3 program to determine minimum  
# number of rotations required to yield  
# same string. 
   
# input 
string = 'aaaa'
check = '' 
   
for r in range(1, len(string)+1): 
  # checking the input after each rotation 
  check = string[r:] + string[:r] 
     
  # following if statement checks if input is  
  # equals to check , if yes it will print r and  
  # break out of the loop 
  if check == string: 
    print(r) 
    break
   
# This code is contributed  
# by nagasowmyanarayanan. 

Output:

This article is contributed by Jatin Goyal. If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute.geeksforgeeks.org or mail your article to contribute@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.

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My Personal Notes

Recommended: Please try your approach on {IDE} first, before moving on to the solution.

C/C++

Java

Python3

C#

PHP

Python3

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