Javascript 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.

Javascript

<script>
// Javascript program to check if a
// string is two time rotation of
// another string.

// Method to check if string2 is
// obtained by string 1
function isRotated(str1, str2)
{
    if (str1.length != str2.length)
        return false;

    if (str1.length < 2)
    {
        return str1.localeCompare(str2);
    }

    let clock_rot = "";
    let anticlock_rot = "";
    let len = str2.length;

    // Initialize string as anti-clockwise
    // rotation
    anticlock_rot = anticlock_rot +
                    str2.substring(len - 2,
                                   len + 1) +
                    str2.substring(0, len - 1) ;

    // Initialize string as clock wise rotation
    clock_rot = clock_rot +
                str2.substring(2, str2.length -
                               2 + 1) +
                str2.substring(0, 2 + 1);

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

// Driver code
let str1 = "geeks";
let str2 = "eksge";
document.write(isRotated(str1, str2) ?
               "Yes" : "No");
// This code is contributed by rag2127
</script>

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!