Java 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.

Java

// Java program to check if a string
// is two time rotation of another string.

class Test
{
    // Method to check if string2 is
    // obtained by string 1
    static boolean isRotated(String str1,
                             String str2)
    {
        if (str1.length() != str2.length())
            return false;
        if(str1.length() < 2)
        {
            return str1.equals(str2);
        }

        String clock_rot = "";
        String anticlock_rot = "";
        int len = str2.length();

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

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

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

    // Driver method
    public static void main(String[] args)
    {
        String str1 = "geeks";
        String str2 = "eksge";

        System.out.println(isRotated(str1, str2) ?
                           "Yes" : "No");
    }
}

Output:

Yes

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

Auxiliary Space: O(n) because using extra space 

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