fun stringChallenge(str: String): String {
    val result = recurseChallenge(str)
    println(result)
    return result.length.toString()
}

fun recurseChallenge(string: String): String {
    val firstChar = string.first()
    val isAllTheSame = string.all { it == firstChar }
    if (isAllTheSame) {
        return string
    } else {
        var position = 0
        val stringIterator = string.iterator()
        var prevValue = stringIterator.nextChar()
        for (item in stringIterator) {
            if (stringIterator.hasNext()) {
                if (item != prevValue) {
                    break
                } else {
                    position++
                }
            }
            prevValue = item
        }
        val oldSequence = string[position] + string[position + 1].toString()
        val newString =
            string.replaceFirst(
                oldSequence,
                checkNeedReplaceOrNot(string[position], string[position + 1]),
                true
            )
        println(newString)
        recurseChallenge(newString)
        return newString
    }
}

fun checkNeedReplaceOrNot(firstChar: Char, secondChar: Char): String = if (firstChar == secondChar) {
    firstChar.toString() + secondChar.toString()
} else {
    thirdChar(firstChar, secondChar)
}

fun thirdChar(firstChar: Char, secondChar: Char): String {
    val twoChar: String = firstChar.toString() + secondChar.toString()
    if (!twoChar.contains("a")) {
        return "a"
    }
    if (!twoChar.contains("b")) {
        return "b"
    }
    if (!twoChar.contains("c")) {
        return "c"
    }
    return twoChar
}

fun main(args: Array<String>) {
    println(stringChallenge("abcabc"))
//    println(stringChallenge(readLine()!!))
}