Check if a string is rotation of another WITHOUT concatenating

Question

There are 2 strings , how can we check if one is a rotated version of another ?

For Example : hello --- lohel

One simple solution is by co

Answer 1

input1= "hello" input2="llohe" input3="lohel"(input3 is special case)

if length's of input 1 & input2 are not same return 0.Let i and j be two indexes pointing to input1 and input2 respectively and initialize count to input1.length. Have a flag called isRotated which is set to false

while(count != 0){

When the character's of input1 matches input2

1. increment i & j
2. decrement count

If the character's donot match

1. if isRotated = true(it means even after rotation there's mismatch) so break;
2. else Reset j to 0 as there's a mismatch. Eg:

Please find the code below and let me know if it fails for some other combination I may not have considered.

    public boolean isRotation(String input1, String input2) {
    boolean isRotated = false;
    int i = 0, j = 0, count = input1.length();

    if (input1.length() != input2.length())
        return false;

    while (count != 0) {

        if (i == input1.length() && !isRotated) {
            isRotated = true;
            i = 0;
        }

        if (input1.charAt(i) == input2.charAt(j)) {
            i++;
            j++;
            count--;
        }

        else {
            if (isRotated) {
                break;
            }
            if (i == input1.length() - 1 && !isRotated) {
                isRotated = true;
            }
            if (i < input1.length()) {
                j = 0;
                count = input1.length();

            }
            /* To handle the duplicates. This is the special case.
             * This occurs when input1 contains two duplicate elements placed side-by-side as "ll" in "hello" while 
             * they may not be side-by-side in input2 such as "lohel" but are still valid rotations. 
             Eg: "hello" "lohel"
            */
            if (input1.charAt(i) == input2.charAt(j)) {
                i--;
            }
            i++;
        }
    }
    if (count == 0)
        return true;
    return false;
}

public static void main(String[] args) {
    // TODO Auto-generated method stub
    System.out.println(new StringRotation().isRotation("harry potter",
            "terharry pot"));
    System.out.println(new StringRotation().isRotation("hello", "llohe"));
    System.out.println(new StringRotation().isRotation("hello", "lohell"));
    System.out.println(new StringRotation().isRotation("hello", "hello"));
    System.out.println(new StringRotation().isRotation("hello", "lohe"));
}