calculator

fun main() {
    print("Введіть математичний вираз: ")
    val expression: String = readLine()!!.toString()
    val lastIndex = expression.lastIndex
    val listNumeric: MutableList<Double> = mutableListOf()
    val listString: MutableList<String> = mutableListOf()
    var counter: Int = 1
    var k: Int = 0
    for (i in expression) {
        if (i == '+' || i == '-' || i == '/' || i == '*' || i == '=') {
            listNumeric.add(expression.dropLast(lastIndex - counter + 2).drop(k).toDouble())
            listString.add(expression[counter - 1].toString())
            k = counter
        }
        counter++
    }
    var result:Double = 0.0
    counter = 0
    listString.forEach {
        if (it == "/") {
            if (listNumeric.get(counter + 1) == 0.0) {
                println("На 0 ділити не можна!")
                return
            }
            result = 0.0
            result += listNumeric.get(counter) / listNumeric.get(counter + 1)
            listNumeric.removeAt(counter + 1)
            listNumeric.removeAt(counter)
            listNumeric.add(counter, result.toDouble())
            counter--

        }
        if (it == "*") {
            result = 0.0
            result += listNumeric.get(counter) * listNumeric.get(counter + 1)
            listNumeric.removeAt(counter + 1)
            listNumeric.removeAt(counter)
            listNumeric.add(counter, result.toDouble())
            counter--
        }
        counter++
    }
    counter = 0
    for (i in listString.indices) {
        if (counter >= listNumeric.size - 1) break
        val operation = listString[i]
        if (operation == "+") {
            result = listNumeric[counter] + listNumeric[counter + 1]
            listNumeric.removeAt(counter + 1)
            listNumeric[counter] = result
            counter--
        } else if (operation == "-") {
            result = listNumeric[counter] - listNumeric[counter + 1]
            listNumeric.removeAt(counter + 1)
            listNumeric[counter] = result
            counter--
        }else continue
        counter++
    }
    println(result)
}