#!/usr/bin/env kotlin
import java.util.Scanner

val scanner = Scanner(System.`in`)

var total = 0L
var totalTwo = 0L
val operations = listOf("*", "+")
while (scanner.hasNext()) {
    val line = scanner.nextLine()
    val (targetString, rest) = line.split(":", limit = 2).map { it.trim() }
    val target = targetString.toLong()
    val values = rest.split(Regex("""\s+""")).map { it.toLong() }
    if (hitsTarget(target, values, operations)) {
        total += target
        totalTwo += target
    } else if (hitsTarget(target, values, listOf("||") + operations)) {
        totalTwo += target
    }
}
println("Total result: $total")
println("Total result (part 2): $totalTwo")

fun hitsTarget(target: Long, values: List<Long>, operations: List<String>): Boolean {
    if (values.size == 1) {
        return target == values[0]
    }
    val (operandOne, operandTwo) = values.take(2)
    if (operandOne > target) {
        return false
    }
    val rest = values.drop(2)
    for (op in operations) {
        val result = when (op) {
            "+" -> operandOne + operandTwo
            "*" -> operandOne * operandTwo
            "||" -> "$operandOne$operandTwo".toLong()
            else -> throw IllegalArgumentException("Unknown operation: $op")
        }
        if (hitsTarget(target, listOf(result) + rest, operations)) {
            return true
        }
    }
    return false
}