areSame.java

    private static boolean areSame(String arr)
    {
        char first = arr.charAt(0);
        for (int i = 1; i < arr.length(); i++)
            if (arr.charAt(i) != first)
                return false;
        return true;
    }

findLongest.java

    private static String findLongestV2(String inputData, int sequenceNumber) {
        int fastPointer;
        String longestString = "";
        int dataLength = inputData.length();
        //forward
        for (int i = 0; i < dataLength; i += sequenceNumber) {
            fastPointer = i + sequenceNumber;
            if (i + sequenceNumber >= dataLength || fastPointer >= dataLength)
                break;
            String block = inputData.substring(i, i + sequenceNumber);
            if (areSame(block)) {
                String nextBlock = "";
                for (int j = fastPointer ; j < dataLength; j++) {
                    nextBlock = nextBlock + inputData.charAt(j);
                    if (!areSame(nextBlock))
                        break;
                    block = block + inputData.charAt(j);
                }

            }
            if (block.length() > longestString.length() )
                longestString = block;
        }
        //reverse
        for (int  i = inputData.length() -1 ; i > 0 ; i-= sequenceNumber) {
            fastPointer = i - sequenceNumber;
            if (i - sequenceNumber < 0 || fastPointer < 0)
                break;
            String block = inputData.substring(i - sequenceNumber, i );
            if (areSame(block)) {
                String nextBlock = "";
                for (int j = fastPointer; j > 0; j--) {
                    nextBlock = nextBlock + inputData.charAt(j);
                    if (!areSame(nextBlock))
                        break;
                    block = block + inputData.charAt(j);
                }
            }
            if (block.length() > longestString.length() )
                longestString = block;
        }
        return longestString;
    }