C++ Program to Check if a string can be obtained by rotating another string 2 places

Given two strings, the task is to find if a string can be obtained by rotating another string two places. 

Examples:

Input: string1 = “amazon”, string2 = “azonam” 
Output: Yes 
// rotated anti-clockwise
Input: string1 = “amazon”, string2 = “onamaz” 
Output: Yes 
// rotated clockwise

Asked in: Amazon Interview

1- There can be only two cases:
    a) Clockwise rotated
    b) Anti-clockwise rotated

2- If clockwise rotated that means elements
   are shifted in right.
   So, check if a substring[2.... len-1] of 
   string2 when concatenated with substring[0,1]
   of string2 is equal to string1. Then, return true.

3- Else, check if it is rotated anti-clockwise 
   that means elements are shifted to left.
   So, check if concatenation of substring[len-2, len-1]
   with substring[0....len-3] makes it equals to
   string1. Then return true.

4- Else, return false.

Below is the implementation of the above approach.

C++

// C++ program to check if a string
// is two time rotation of another string.
#include<bits/stdc++.h>
using namespace std;

// Function to check if string2 is
// obtained by string 1
bool isRotated(string str1,
               string str2)
{
    if (str1.length() != str2.length())
        return false;
    if(str1.length()<2){
      return str1.compare(str2) == 0;
    }
    string clock_rot = "";
    string anticlock_rot = "";
    int len = str2.length();

    // Initialize string as anti-clockwise
    // rotation
    anticlock_rot = anticlock_rot +
                    str2.substr(len-2, 2) +
                    str2.substr(0, len-2) ;

    // Initialize string as clock wise
    // rotation
    clock_rot = clock_rot +
                str2.substr(2) +
                str2.substr(0, 2) ;

    // check if any of them is equal
    // to string1
    return (str1.compare(clock_rot) == 0 ||
            str1.compare(anticlock_rot) == 0);
}

// Driver code
int main()
{
    string str1 = "geeks";
    string str2 = "eksge";

    isRotated(str1, str2) ? cout << "Yes"
                          : cout << "No";
    return 0;
}

Output:

Yes

Time Complexity: O(n), where n is the size of the given string.

Please refer complete article on Check if a string can be obtained by rotating another string 2 places for more details!