Check if left and right shift of any string results into given string

Difficulty Level : Medium
Last Updated : 21 May, 2021

Given string S consisting of only lowercase English letters. The task is to find if there exists any string which has left shift and right shift both equal to string S. If there exists any string then print Yes, otherwise print No.
Examples:

Input: S = “abcd”
Output: No
Explanation:
There is no string which have left shift and right shift both equal to string “abcd”.
Input: papa
Output: Yes
Explanation:
The left shift and right shift both of string “apap” equals to string “papa”.

Approach:

The main target is to check the left shift and right shift both of any string equals to given string or not.
For that we just have to check every character of given string is equal to its next to next character or not (i.e. character at (i)^th position must be equal to character at (i+2)^th position ).
If it’s true for every position on the given stringm then we can say there exist any string whose left shift and right shift equal to given string otherwise not.

Below is the implementation of the above approach:

C++

// C++ program to check if left
// and right shift of any string
// results into the given string
 
#include <bits/stdc++.h>
using namespace std;
 
// Function to check string exist
// or not as per above approach
void check_string_exist(string S)
{
    int size = S.length();
 
    bool check = true;
 
    for (int i = 0; i < size; i++) {
 
        // Check if any character
        // at position i and i+2
        // are not equal
        // then string doesnot exist
        if (S[i] != S[(i + 2) % size]) {
            check = false;
            break;
        }
    }
 
    if (check)
        cout << "Yes" << endl;
    else
        cout << "No" << endl;
}
 
// Driver code
int main()
{
    string S = "papa";
 
    check_string_exist(S);
 
    return 0;
}

Java

// Java program to check if left
// and right shift of any string
// results into the given string
class GFG{
     
// Function to check string exist
// or not as per above approach
public static void check_string_exist(String S)
{
    int size = S.length();
    boolean check = true;
     
    for(int i = 0; i < size; i++)
    {
        
       // Check if any character
       // at position i and i+2
       // are not equal
       // then string doesnot exist
       if (S.charAt(i) != S.charAt((i + 2) % size))
       {
           check = false;
           break;
       }
    }
     
    if (check)
        System.out.println("Yes");
    else
        System.out.println("No");
}
 
// Driver Code
public static void main(String[] args)
{
    String S = "papa";
     
    check_string_exist(S);
}
}
 
// This code is contributed by divyeshrabadiya07

Python3

# Python3 program to check if left
# and right shift of any string
# results into the given string
 
# Function to check string exist
# or not as per above approach
def check_string_exist(S):
     
    size = len(S)
    check = True
     
    for i in range(size):
         
        # Check if any character
        # at position i and i+2
        # are not equal, then 
        # string doesnot exist
        if S[i] != S[(i + 2) % size]:
            check = False
            break
         
    if check :
        print("Yes")
    else:
        print("No")
 
# Driver Code
S = "papa"
 
check_string_exist(S)
 
# This code is contributed by divyeshrabadiya07

C#

// C# program to check if left
// and right shift of any string
// results into the given string
using System;
 
class GFG{
     
// Function to check string exist
// or not as per above approach
public static void check_string_exist(String S)
{
    int size = S.Length;
    bool check = true;
     
    for(int i = 0; i < size; i++)
    {
         
       // Check if any character
       // at position i and i+2
       // are not equal
       // then string doesnot exist
       if (S[i] != S[(i + 2) % size])
       {
           check = false;
           break;
       }
    }
    if (check)
        Console.WriteLine("Yes");
    else
        Console.WriteLine("No");
}
 
// Driver Code
public static void Main(String[] args)
{
    String S = "papa";
     
    check_string_exist(S);
}
}
 
// This code is contributed by sapnasingh4991

Javascript

<script>
 
// Javasript program to check if left
// and right shift of any string
// results into the given string
 
// Function to check string exist
// or not as per above approach
function check_string_exist(S)
{
    var size = S.length;
 
    var check = true;
 
    for (var i = 0; i < size; i++) {
 
        // Check if any character
        // at position i and i+2
        // are not equal
        // then string doesnot exist
        if (S[i] != S[(i + 2) % size]) {
            check = false;
            break;
        }
    }
 
    if (check)
        document.write( "Yes" );
    else
        document.write( "No" );
}
 
// Driver code
var S = "papa";
check_string_exist(S);
 
// This code is contributed by noob2000.
</script>

Output:

Yes

Time Complexity: O(N) where N is the size of the string S.
Auxiliary Space Complexity: O(1)

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